Significant Accounting Policies Update	3 Months Ended
Mar. 31, 2018
Accounting Policies [Abstract]
Significant Accounting Policies Update	2. Significant Accounting Policies Update Revenue Recognition We account for revenue in accordance with Accounting Standards Codification (ASC) Topic 606, “Revenue from Contracts with Customers.” Topic 606 also includes Subtopic 340-40, “Other Assets and Deferred Costs – Contracts with Customers,” which requires deferral of incremental costs to obtain and fulfill a contract with a customer. We adopted new revenue recognition guidance on January 1, 2018, using the full retrospective method (see Note 3). Revenue is recognized when or as control of the promised services is transferred to our customers, in an amount that reflects the consideration we expect to be entitled to in exchange for those services. The following is a description of principal activities – separated by reportable segments – from which we generate revenue. For more detailed information about our reportable segments, see Notes 11 and 12. The Americas, Europe, Middle East and Africa (EMEA), and Asia Pacific The Americas segment is our largest segment of operations and provides a comprehensive range of services throughout the United States (U.S.), in the largest regions of Canada and in key markets in Latin America. The primary services offered consist of the following: property leasing, property sales, mortgage services, appraisal and valuation, occupier outsourcing and property management services. Our EMEA and Asia Pacific segments generally provide services similar to the Americas business segment. The EMEA segment has operations primarily in Europe, while the Asia Pacific segment has operations in Asia, Australia and New Zealand. Property Leasing and Property Sales Through our Advisory & Transaction Services business line, we provide strategic advice and execution to owners, investors, and occupiers of real estate in connection with the leasing of office, industrial and retail space. We also offer clients fully integrated property sales services under the CBRE Capital Markets brand. We are compensated for our services in the form of a commission and, in some instances may earn various forms of variable incentive consideration. Our commission is paid upon the occurrence of certain contractual event(s) which may be contingent. For example, a portion of our leasing commission may be paid upon signing of the lease by the tenant, with the remaining paid upon occurrence of another future contingent event (e.g. payment of first month’s rent or tenant move-in). For sales, our commission is typically paid at the closing of the sale. We typically satisfy our performance obligation at a point in time when control is transferred; generally, at the time of the first contractual event where there is a present right to payment. We look to history, experience with a customer, and deal specific considerations to support our judgement that the second contingency (if applicable) will be met. Therefore, we typically accelerate the recognition of the revenue associated with the second contingent event. In addition to our commission, we may recognize other forms of variable consideration which can include, but are not limited to, commissions subject to concession or claw back and volume based discounts or rebates. We assess variable consideration on a contract by contract basis, and when appropriate, recognize revenue based on our assessment of the outcome (using the most likely outcome approach or weighted probability) and historical results, if comparable and representative. We recognize variable consideration if it is deemed probable that there will not be significant reversal in the future. Mortgage Originations and Loan Sales Under the CBRE Capital Markets brand, we offer clients fully integrated commercial mortgage and structured financing services. Fees from services within our mortgage brokerage business that are in the scope of Topic 606 include fees earned for the brokering of commercial mortgage loans primarily through relationships established with investment banking firms, national and regional banks, credit companies, insurance companies and pension funds. We are compensated for our brokerage services via a fee paid upon successful placement of a commercial mortgage borrower with a lender who will provide financing. The fee earned is contingent upon the funding of the loan. We typically satisfy our performance obligation when control is transferred at the point in time of the funding of the loan. We also earn fees from the origination and sale of commercial mortgage loans for which the company retains the servicing rights. These fees are governed by the “Fair Value Measurements and Disclosures” topic (Topic 820) and “Transfers and Servicing” topic (Topic 860) of the FASB ASC. Upon origination of a mortgage loan held for sale, the fair value of the mortgage servicing rights (MSR) to be retained is included in the forecasted proceeds from the anticipated loan sale and results in a net gain (which is reflected in revenue). Upon sale, we record a servicing asset or liability based on the fair value of the retained MSR associated with the transferred loan. Subsequent to the initial recording, MSRs are amortized and carried at the lower of amortized cost or fair value in other intangible assets in the accompanying consolidated balance sheets. They are amortized in proportion to and over the estimated period that the servicing income is expected to be received. Appraisal and Valuation We provide valuation services that include market-value appraisals, litigation support, discounted cash flow analyses, feasibility studies as well as consulting services such as property condition reports, hotel advisory and environmental consulting. We are compensated for valuation services in the form of a fee, which is payable on the occurrence of certain events (e.g. a portion on the delivery of a draft report with the remaining on the delivery of the final report). For consulting services, we may be paid based on the occurrence of time or event-based milestones (such as the delivery of draft reports). We typically satisfy our performance obligation as services are rendered over time. Occupier Outsourcing Services We provide a broad suite of services to occupiers of real estate, including facilities management, project management, transaction management and strategic consulting. We report facilities and project management as well as strategic consulting activities in our occupier outsourcing revenue line and transaction management in our lease and sales revenue lines. Facilities management involves the day-to-day management of client-occupied space and includes headquarter buildings, regional offices, administrative offices, data centers and other critical facilities, manufacturing and laboratory facilities, distribution facilities and retail space. Contracts for facilities management services are often structured so we are reimbursed for client-dedicated personnel costs and subcontracted vendor costs as well as associated overhead expenses plus a monthly fee, and, in some cases, annual incentives tied to agreed-upon performance targets, with any penalties typically capped. Facilities management services represent a series of distinct daily services rendered over time. Project management services are often provided on a portfolio wide or programmatic basis. Revenues from project management services generally includes fixed management fees, variable fees, and incentive fees if certain agreed-upon performance targets are met. Revenues from project management may also include reimbursement of payroll and related costs for personnel providing the services and subcontracted vendor costs. Project management services represent a series of distinct daily services rendered over time. The amount of revenue recognized is presented gross for any services provided by our employees, as we control them. This is evidenced by our obligation for their performance and our ability to direct and redirect their work, as well as negotiate the value of such services. The amount of revenue recognized related to the majority of facilities management contracts and certain project management arrangements is presented gross (with offsetting expense recorded in cost of services) for reimbursements of costs of third-party services because we control those services that are delivered to the client. In the instances when we do not control third-party services delivered to the client, we report revenues net of the third-party reimbursements. In addition to our management fee, we receive various types of variable consideration which can include, but is not limited to; key performance indicator bonuses or penalties which may be linked to subcontractor performance, gross maximum price, glidepaths, savings guarantees, shared savings, or fixed fee structures. We assess variable consideration on a contract by contract basis, and when appropriate, recognize revenue based on our assessment of the outcome (using the most likely outcome approach or weighted probability) and historical results, if comparable and representative. Using management assessment and historical results and statistics, we accelerate revenue if it is deemed probable there will not be significant reversal in the future. Property Management We provide property management services on a contractual basis for owners of and investors in office, industrial and retail properties. These services include construction management, marketing, building engineering, accounting and financial services. We are compensated for our services through a monthly management fee earned based on either a specified percentage of the monthly rental income, rental receipts generated from the property under management or a fixed fee. We are also often reimbursed for our administrative and payroll costs directly attributable to the properties under management. Property management services represent a series of distinct daily services rendered over time. The amount of revenue recognized is presented gross for any services provided by our employees, as we control them. We generally do not control third-party services delivered to property management clients. As such, we report revenues net of third-party reimbursements. Global Investment Management Our Global Investment Management business segment provides investment management services to pension funds, insurance companies, sovereign wealth funds, foundations, endowments and other institutional investors seeking to generate returns and diversification through investment in real estate. We sponsor investment programs that span the risk/return spectrum in: North America, Europe, Asia and Australia. We are typically compensated in the form of a base management fee, disposition fees, acquisition fees and incentive fees in the form of performance fees or carried interest based on fund type (open or closed ended, respectively). For the base management fee, we typically satisfy the performance obligation as service is rendered over time pursuant to the series guidance. For acquisition and disposition services, we typically satisfy the performance obligation at a point in time (at acquisition or upon disposition). For contracts with contingent fees, including performance fees, incentive fees and carried interest, we assess variable consideration on a contract by contract basis, and when appropriate, recognize revenue based on our assessment of the outcome (using the most likely outcome approach or weighted probability) and historical results, if comparable and representative. Revenue associated with performance fees and carried interest are typically constrained due to volatility in the real estate market, a broad range of possible outcomes, and other factors in the market that are outside of our control. Development Services Our Development Services business segment consists of real estate development and investment activities primarily in the United States to users of and investors in commercial real estate, as well as for our own account. We pursue opportunistic, risk-mitigated development and investment in commercial real estate across a wide spectrum of property types, including: industrial, office and retail properties; healthcare facilities of all types (medical office buildings, hospitals and ambulatory surgery centers); and residential/mixed-use projects. We pursue development and investment activity on behalf of our clients on a fee basis with no, or limited, ownership interest in a property, in partnership with our clients through co-investment – either on an individual project basis or through programs with certain strategic capital partners or for our own account with 100% ownership. Development services represent a series of distinct daily services rendered over time. Fees are typically payable monthly over the service term or upon contractual defined events, like project milestones. In addition to development fee revenue, we receive various types of variable consideration which can include, but is not limited to, contingent lease-up bonuses, cost saving incentives, profit sharing on sales and at-risk fees. We assess variable consideration on a contract by contract basis, and when appropriate, recognize revenue based on our assessment of the outcome (using the most likely outcome approach or weighted probability) and historical results, if comparable and representative. We accelerate revenue if it is deemed probable there will not be significant reversal in the future. Accounts Receivable and Allowance for Doubtful Accounts We record accounts receivable for our unconditional rights to consideration arising from our performance under contracts with customers. The carrying value of such receivables, net of the allowance for doubtful accounts, represents their estimated net realizable value. We estimate our allowance for doubtful accounts for specific accounts receivable balances based on historical collection trends, the age of outstanding accounts receivables and existing economic conditions associated with the receivables. Past-due accounts receivable balances are written off when our internal collection efforts have been unsuccessful. As a practical expedient, we do not adjust the promised amount of consideration for the effects of a significant financing component when we expect, at contract inception, that the period between our transfer of a promised service to a customer and when the customer pays for that service will be one year or less. We do not typically include extended payment terms in our contracts with customers. Remaining Performance Obligations Remaining performance obligations represent the aggregate transaction prices for contracts where our performance obligations have not yet been satisfied. As of March 31, 2018, the aggregate amount of transaction price allocated to remaining performance obligations in our property leasing business represented less than 2% of our total revenue. We apply the practical expedient related to remaining performance obligations that are part of a contract that has an original expected duration of one year or less and the practical expedient related to variable consideration from remaining performance obligations pursuant to the series guidance. All of our remaining performance obligations apply to one of these practical expedients. Contract Assets and Contract Liabilities Contract assets represent assets for revenue that has been recognized in advance of billing the customer and for which the right to bill is contingent upon something other than the passage of time. This is common for contingent portions of commissions in brokerage and incentive fees present in various businesses. Billing requirements vary by contract but are generally structured around fixed monthly fees, reimbursement of employee and other third-party costs, and the achievement or completion of certain contingent events. When we receive consideration, or such consideration is unconditionally due, from a customer prior to transferring services to the customer under the terms of the services contract, we record deferred revenue, which represents a contract liability. Such deferred revenue typically results from milestone payments pertaining to future services not yet rendered. We recognize the contract liability as revenue once we have transferred control of service to the customer and all revenue recognition criteria are met. Contract assets and contract liabilities are determined for each contract on a net basis. For contract assets, we classify the short-term portion as a separate line item within other current assets and the long-term portion within other assets, long-term in the accompanying consolidated balance sheets. Contract liabilities are classified as a separate line item within other current liabilities in the accompanying consolidated balance sheets. Contract Costs Contract costs primarily consist of upfront costs incurred to obtain or to fulfill a contract. These costs are typically found within our Occupier Outsourcing business line. Such costs relate to transition costs to fulfill contracts prior to services being rendered. Capitalized transition costs are amortized based on the transfer of services to which the assets relate which can vary on a contract by contract basis, and are included in cost of services in the accompanying consolidated statement of operations. For contract costs that are recognized as assets, we periodically review for impairment. Applying the contract cost practical expedient, we recognize the incremental costs of obtaining contracts as an expense when incurred if the amortization period of the assets that we otherwise would have recognized is one year or less. Income Taxes On December 22, 2017, the Tax Cuts and Jobs Act (Tax Act) was signed into law making significant changes to the Internal Revenue Code, including, but not limited to: (i) a U.S. corporate tax rate decrease from 35% to 21%, effective for tax years beginning after December 31, 2017; (ii) the transition of U.S. international taxation from a worldwide tax system to a territorial system; and (iii) a one-time transition tax on the mandatory deemed repatriation of cumulative foreign earnings as of December 31, 2017. In December 2017, the SEC staff issued Staff Accounting Bulletin No. 118 (SAB 118), “Income Tax Accounting Implications of the Tax Cuts and Jobs Act,” which allows us to record provisional amounts during a measurement period not to extend beyond one year of the enactment date. In March 2018, the Financial Accounting Standards Board (FASB) issued ASU 2018-05, “Income Taxes (Topic 740): Amendments to SEC Paragraphs Pursuant to SEC Staff Accounting Bulletin No. 118,” which added SEC guidance related to SAB 118. Our provision for income taxes for 2017 included a provisional amount related to our estimate of the U.S. federal and state tax impact of the transition tax and other components of the Tax Act. In the first quarter of 2018, we obtained additional information affecting the provisional amount initially recorded for the transition tax. As a result, we recorded an immaterial adjustment to the transition tax in the tax provision for the three months ended March 31, 2018. Provisional amounts that have been recorded are based upon our best estimate of the impact of the Tax Act in accordance with our understanding of the Tax Act and the related guidance available. Additional work is necessary on the provisional amount related to the transition tax, which includes performing a more detailed analysis of historic foreign earnings and tax pools and potential corresponding adjustments. See Note 2 of the Notes to Consolidated Financial Statements set forth in Item 8 included in our Annual Report on Form 10-K for the year ended December 31, 2017 for a summary of our other significant accounting policies.

2. Significant Accounting Policies Update

Revenue Recognition

We account for revenue in accordance with Accounting Standards Codification (ASC) Topic 606, “Revenue from Contracts with Customers.” Topic 606 also includes Subtopic 340-40, “Other Assets and Deferred Costs – Contracts with Customers,” which requires deferral of incremental costs to obtain and fulfill a contract with a customer. We adopted new revenue recognition guidance on January 1, 2018, using the full retrospective method (see Note 3). Revenue is recognized when or as control of the promised services is transferred to our customers, in an amount that reflects the consideration we expect to be entitled to in exchange for those services.

The following is a description of principal activities – separated by reportable segments – from which we generate revenue. For more detailed information about our reportable segments, see Notes 11 and 12.

The Americas, Europe, Middle East and Africa (EMEA), and Asia Pacific

The Americas segment is our largest segment of operations and provides a comprehensive range of services throughout the United States (U.S.), in the largest regions of Canada and in key markets in Latin America. The primary services offered consist of the following: property leasing, property sales, mortgage services, appraisal and valuation, occupier outsourcing and property management services.

Our EMEA and Asia Pacific segments generally provide services similar to the Americas business segment. The EMEA segment has operations primarily in Europe, while the Asia Pacific segment has operations in Asia, Australia and New Zealand.

Property Leasing and Property Sales

Through our Advisory & Transaction Services business line, we provide strategic advice and execution to owners, investors, and occupiers of real estate in connection with the leasing of office, industrial and retail space. We also offer clients fully integrated property sales services under the CBRE Capital Markets brand. We are compensated for our services in the form of a commission and, in some instances may earn various forms of variable incentive consideration. Our commission is paid upon the occurrence of certain contractual event(s) which may be contingent. For example, a portion of our leasing commission may be paid upon signing of the lease by the tenant, with the remaining paid upon occurrence of another future contingent event (e.g. payment of first month’s rent or tenant move-in). For sales, our commission is typically paid at the closing of the sale. We typically satisfy our performance obligation at a point in time when control is transferred; generally, at the time of the first contractual event where there is a present right to payment. We look to history, experience with a customer, and deal specific considerations to support our judgement that the second contingency (if applicable) will be met. Therefore, we typically accelerate the recognition of the revenue associated with the second contingent event.

In addition to our commission, we may recognize other forms of variable consideration which can include, but are not limited to, commissions subject to concession or claw back and volume based discounts or rebates. We assess variable consideration on a contract by contract basis, and when appropriate, recognize revenue based on our assessment of the outcome (using the most likely outcome approach or weighted probability) and historical results, if comparable and representative. We recognize variable consideration if it is deemed probable that there will not be significant reversal in the future.

Mortgage Originations and Loan Sales

Under the CBRE Capital Markets brand, we offer clients fully integrated commercial mortgage and structured financing services. Fees from services within our mortgage brokerage business that are in the scope of Topic 606 include fees earned for the brokering of commercial mortgage loans primarily through relationships established with investment banking firms, national and regional banks, credit companies, insurance companies and pension funds. We are compensated for our brokerage services via a fee paid upon successful placement of a commercial mortgage borrower with a lender who will provide financing. The fee earned is contingent upon the funding of the loan. We typically satisfy our performance obligation when control is transferred at the point in time of the funding of the loan.

We also earn fees from the origination and sale of commercial mortgage loans for which the company retains the servicing rights. These fees are governed by the “Fair Value Measurements and Disclosures” topic (Topic 820) and “Transfers and Servicing” topic (Topic 860) of the FASB ASC. Upon origination of a mortgage loan held for sale, the fair value of the mortgage servicing rights (MSR) to be retained is included in the forecasted proceeds from the anticipated loan sale and results in a net gain (which is reflected in revenue). Upon sale, we record a servicing asset or liability based on the fair value of the retained MSR associated with the transferred loan. Subsequent to the initial recording, MSRs are amortized and carried at the lower of amortized cost or fair value in other intangible assets in the accompanying consolidated balance sheets. They are amortized in proportion to and over the estimated period that the servicing income is expected to be received.

Appraisal and Valuation

We provide valuation services that include market-value appraisals, litigation support, discounted cash flow analyses, feasibility studies as well as consulting services such as property condition reports, hotel advisory and environmental consulting. We are compensated for valuation services in the form of a fee, which is payable on the occurrence of certain events (e.g. a portion on the delivery of a draft report with the remaining on the delivery of the final report). For consulting services, we may be paid based on the occurrence of time or event-based milestones (such as the delivery of draft reports). We typically satisfy our performance obligation as services are rendered over time.

Occupier Outsourcing Services

We provide a broad suite of services to occupiers of real estate, including facilities management, project management, transaction management and strategic consulting. We report facilities and project management as well as strategic consulting activities in our occupier outsourcing revenue line and transaction management in our lease and sales revenue lines.

Facilities management involves the day-to-day management of client-occupied space and includes headquarter buildings, regional offices, administrative offices, data centers and other critical facilities, manufacturing and laboratory facilities, distribution facilities and retail space. Contracts for facilities management services are often structured so we are reimbursed for client-dedicated personnel costs and subcontracted vendor costs as well as associated overhead expenses plus a monthly fee, and, in some cases, annual incentives tied to agreed-upon performance targets, with any penalties typically capped. Facilities management services represent a series of distinct daily services rendered over time.

Project management services are often provided on a portfolio wide or programmatic basis. Revenues from project management services generally includes fixed management fees, variable fees, and incentive fees if certain agreed-upon performance targets are met. Revenues from project management may also include reimbursement of payroll and related costs for personnel providing the services and subcontracted vendor costs. Project management services represent a series of distinct daily services rendered over time.

The amount of revenue recognized is presented gross for any services provided by our employees, as we control them. This is evidenced by our obligation for their performance and our ability to direct and redirect their work, as well as negotiate the value of such services. The amount of revenue recognized related to the majority of facilities management contracts and certain project management arrangements is presented gross (with offsetting expense recorded in cost of services) for reimbursements of costs of third-party services because we control those services that are delivered to the client. In the instances when we do not control third-party services delivered to the client, we report revenues net of the third-party reimbursements.

In addition to our management fee, we receive various types of variable consideration which can include, but is not limited to; key performance indicator bonuses or penalties which may be linked to subcontractor performance, gross maximum price, glidepaths, savings guarantees, shared savings, or fixed fee structures. We assess variable consideration on a contract by contract basis, and when appropriate, recognize revenue based on our assessment of the outcome (using the most likely outcome approach or weighted probability) and historical results, if comparable and representative. Using management assessment and historical results and statistics, we accelerate revenue if it is deemed probable there will not be significant reversal in the future.

Property Management

We provide property management services on a contractual basis for owners of and investors in office, industrial and retail properties. These services include construction management, marketing, building engineering, accounting and financial services. We are compensated for our services through a monthly management fee earned based on either a specified percentage of the monthly rental income, rental receipts generated from the property under management or a fixed fee. We are also often reimbursed for our administrative and payroll costs directly attributable to the properties under management. Property management services represent a series of distinct daily services rendered over time. The amount of revenue recognized is presented gross for any services provided by our employees, as we control them. We generally do not control third-party services delivered to property management clients. As such, we report revenues net of third-party reimbursements.

Global Investment Management

Our Global Investment Management business segment provides investment management services to pension funds, insurance companies, sovereign wealth funds, foundations, endowments and other institutional investors seeking to generate returns and diversification through investment in real estate. We sponsor investment programs that span the risk/return spectrum in: North America, Europe, Asia and Australia. We are typically compensated in the form of a base management fee, disposition fees, acquisition fees and incentive fees in the form of performance fees or carried interest based on fund type (open or closed ended, respectively). For the base management fee, we typically satisfy the performance obligation as service is rendered over time pursuant to the series guidance. For acquisition and disposition services, we typically satisfy the performance obligation at a point in time (at acquisition or upon disposition). For contracts with contingent fees, including performance fees, incentive fees and carried interest, we assess variable consideration on a contract by contract basis, and when appropriate, recognize revenue based on our assessment of the outcome (using the most likely outcome approach or weighted probability) and historical results, if comparable and representative. Revenue associated with performance fees and carried interest are typically constrained due to volatility in the real estate market, a broad range of possible outcomes, and other factors in the market that are outside of our control.

Development Services

Our Development Services business segment consists of real estate development and investment activities primarily in the United States to users of and investors in commercial real estate, as well as for our own account. We pursue opportunistic, risk-mitigated development and investment in commercial real estate across a wide spectrum of property types, including: industrial, office and retail properties; healthcare facilities of all types (medical office buildings, hospitals and ambulatory surgery centers); and residential/mixed-use projects. We pursue development and investment activity on behalf of our clients on a fee basis with no, or limited, ownership interest in a property, in partnership with our clients through co-investment – either on an individual project basis or through programs with certain strategic capital partners or for our own account with 100% ownership. Development services represent a series of distinct daily services rendered over time. Fees are typically payable monthly over the service term or upon contractual defined events, like project milestones. In addition to development fee revenue, we receive various types of variable consideration which can include, but is not limited to, contingent lease-up bonuses, cost saving incentives, profit sharing on sales and at-risk fees. We assess variable consideration on a contract by contract basis, and when appropriate, recognize revenue based on our assessment of the outcome (using the most likely outcome approach or weighted probability) and historical results, if comparable and representative. We accelerate revenue if it is deemed probable there will not be significant reversal in the future.

Accounts Receivable and Allowance for Doubtful Accounts

We record accounts receivable for our unconditional rights to consideration arising from our performance under contracts with customers. The carrying value of such receivables, net of the allowance for doubtful accounts, represents their estimated net realizable value. We estimate our allowance for doubtful accounts for specific accounts receivable balances based on historical collection trends, the age of outstanding accounts receivables and existing economic conditions associated with the receivables. Past-due accounts receivable balances are written off when our internal collection efforts have been unsuccessful. As a practical expedient, we do not adjust the promised amount of consideration for the effects of a significant financing component when we expect, at contract inception, that the period between our transfer of a promised service to a customer and when the customer pays for that service will be one year or less. We do not typically include extended payment terms in our contracts with customers.

Remaining Performance Obligations

Remaining performance obligations represent the aggregate transaction prices for contracts where our performance obligations have not yet been satisfied. As of March 31, 2018, the aggregate amount of transaction price allocated to remaining performance obligations in our property leasing business represented less than 2% of our total revenue. We apply the practical expedient related to remaining performance obligations that are part of a contract that has an original expected duration of one year or less and the practical expedient related to variable consideration from remaining performance obligations pursuant to the series guidance. All of our remaining performance obligations apply to one of these practical expedients.

Contract Assets and Contract Liabilities

Contract assets represent assets for revenue that has been recognized in advance of billing the customer and for which the right to bill is contingent upon something other than the passage of time. This is common for contingent portions of commissions in brokerage and incentive fees present in various businesses. Billing requirements vary by contract but are generally structured around fixed monthly fees, reimbursement of employee and other third-party costs, and the achievement or completion of certain contingent events.

When we receive consideration, or such consideration is unconditionally due, from a customer prior to transferring services to the customer under the terms of the services contract, we record deferred revenue, which represents a contract liability. Such deferred revenue typically results from milestone payments pertaining to future services not yet rendered. We recognize the contract liability as revenue once we have transferred control of service to the customer and all revenue recognition criteria are met.

Contract assets and contract liabilities are determined for each contract on a net basis. For contract assets, we classify the short-term portion as a separate line item within other current assets and the long-term portion within other assets, long-term in the accompanying consolidated balance sheets. Contract liabilities are classified as a separate line item within other current liabilities in the accompanying consolidated balance sheets.

Contract Costs

Contract costs primarily consist of upfront costs incurred to obtain or to fulfill a contract. These costs are typically found within our Occupier Outsourcing business line. Such costs relate to transition costs to fulfill contracts prior to services being rendered. Capitalized transition costs are amortized based on the transfer of services to which the assets relate which can vary on a contract by contract basis, and are included in cost of services in the accompanying consolidated statement of operations. For contract costs that are recognized as assets, we periodically review for impairment.

Applying the contract cost practical expedient, we recognize the incremental costs of obtaining contracts as an expense when incurred if the amortization period of the assets that we otherwise would have recognized is one year or less.

Income Taxes

On December 22, 2017, the Tax Cuts and Jobs Act (Tax Act) was signed into law making significant changes to the Internal Revenue Code, including, but not limited to: (i) a U.S. corporate tax rate decrease from 35% to 21%, effective for tax years beginning after December 31, 2017; (ii) the transition of U.S. international taxation from a worldwide tax system to a territorial system; and (iii) a one-time transition tax on the mandatory deemed repatriation of cumulative foreign earnings as of December 31, 2017. In December 2017, the SEC staff issued Staff Accounting Bulletin No. 118 (SAB 118), “Income Tax Accounting Implications of the Tax Cuts and Jobs Act,” which allows us to record provisional amounts during a measurement period not to extend beyond one year of the enactment date. In March 2018, the Financial Accounting Standards Board (FASB) issued ASU 2018-05, “Income Taxes (Topic 740): Amendments to SEC Paragraphs Pursuant to SEC Staff Accounting Bulletin No. 118,” which added SEC guidance related to SAB 118. Our provision for income taxes for 2017 included a provisional amount related to our estimate of the U.S. federal and state tax impact of the transition tax and other components of the Tax Act. In the first quarter of 2018, we obtained additional information affecting the provisional amount initially recorded for the transition tax. As a result, we recorded an immaterial adjustment to the transition tax in the tax provision for the three months ended March 31, 2018. Provisional amounts that have been recorded are based upon our best estimate of the impact of the Tax Act in accordance with our understanding of the Tax Act and the related guidance available. Additional work is necessary on the provisional amount related to the transition tax, which includes performing a more detailed analysis of historic foreign earnings and tax pools and potential corresponding adjustments.

See Note 2 of the Notes to Consolidated Financial Statements set forth in Item 8 included in our Annual Report on Form 10-K for the year ended December 31, 2017 for a summary of our other significant accounting policies.