Organization and Significant Accounting Policies (Policies)	9 Months Ended
Sep. 30, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation and Principles of Consolidation	The financial information presented in the accompanying unaudited condensed consolidated financial statements has been prepared in accordance with U.S. generally accepted accounting principles (“U.S. GAAP”) and in accordance with rules and regulations of the U.S. Securities and Exchange Commission (“SEC”) regarding interim financial reporting. Accordingly, the financial statements do not include all of the information and footnotes required by U.S. GAAP for complete financial statements. The condensed consolidated balance sheet data as of December 31, 2016 was derived from audited financial statements, but does not include all disclosures required by U.S. GAAP. In the opinion of management, the accompanying unaudited condensed consolidated financial statements reflect all adjustments, consisting primarily of normal recurring accruals, necessary for a fair presentation of our financial position and results of operations. The operating results for the three and nine months ended September 30, 2017 are not necessarily indicative of the results expected for the full year ending December 31, 2017.
Use of Estimates	The preparation of consolidated financial statements in conformity with U.S. GAAP requires us to make estimates and assumptions that affect the amounts reported in the consolidated financial statements and accompanying notes. We base our estimates on historical experience and various other assumptions believed to be reasonable. These estimates include, but are not limited to, the determination of the relative selling prices of our services, health insurance claims incurred but not yet reported, collectability of accounts receivable, valuation of available-for-sale marketable securities, useful lives of intangible assets and property and equipment, income taxes and certain assumptions used in the valuation of equity awards. While these estimates are based on our best knowledge of current events and actions that may affect us in the future, actual results may differ materially from these estimates.
Recently Adopted Accounting Pronouncements and New Accounting Pronouncements Not Yet Adopted	Recently Adopted Accounting Pronouncements In March 2016, the FASB issued ASU 2016-09, Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting. Under this ASU, entities are permitted to make an accounting policy election to either estimate forfeitures on share-based payment awards, as required by current guidance, or to recognize forfeitures as they occur in addition to other changes. The guidance became effective for interim and annual periods beginning after December 15, 2016. Effective January 1, 2017, we adopted this standard. We elected to recognize forfeitures on share-based payment awards as they occur. The adoption, along with the remaining provisions of ASU 2016-09, did not have a material impact on our consolidated financial statements. In October 2016, the FASB issued ASU 2016-16, Income Taxes - Intra-Entity Transfers of Assets Other Than Inventory, which requires entities to recognize the income tax consequences of an intra-entity transfer of an asset other than inventory when the transfer occurs. The new guidance is effective for annual reporting periods beginning after December 15, 2017. Early adoption is permitted as of the beginning of an annual reporting period. The new standard must be adopted using a modified retrospective transition method, with the cumulative effect recognized as of the date of initial adoption. Effective January 1, 2017, we adopted this standard. The adoption of this new guidance did not have a material impact on our consolidated financial statements. New Accounting Pronouncements Not Yet Adopted In May 2014, the Financial Accounting Standards Board (FASB) issued guidance codified in ASC 606, Revenue Recognition - Revenue from Contracts with Customers (ASU 2014-09), which amends the guidance in former ASC 605, Revenue Recognition. The core principle of ASU 2014-09 is that an entity should recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. Additionally, the guidance requires improved disclosures to help users of financial statements better understand the nature, amount, timing, and uncertainty of revenue and cash flows arising from contracts with customers. The FASB has issued several amendments and updates to the new revenue standard, including guidance related to when an entity should recognize revenue gross as a principal or net as an agent and how an entity should identify performance obligations. As amended, ASU 2014-09 is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2017. Early adoption is permitted for all entities only as of annual reporting periods beginning after December 15, 2016, including interim reporting periods within that reporting period. We believe the adoption of ASU 2014-09 will require us to recognize revenue from certain of our professional services over time rather than upon completion of the services. We expect this change may result in some acceleration of revenue recognition. We have determined that an agreement to purchase our professional services constitutes an option to purchase services in accordance with ASC 606-10-55-41 rather than an agreement that creates enforceable rights and obligations because of the customer’s contractual right to cancel the unused services. Based on our review, certain of our professional service agreements do not contain a material right and are only accounted for in accordance with ASU 2014-09 when the customer exercises its option to purchase additional goods or services. In the case of agreements where we have determined that the option provides the customer with a material right, we will be required to allocate a portion of the transaction price to the material right. The treatment of customer options under ASU 2014-09 may result in a different allocation of the transaction price than under current guidance. In addition, under current guidance, the amount that is allocated to, and recognized as revenue related to, a delivered service is limited to the amount that is not contingent on completion of the remaining performance obligations. We expect the removal of this limitation on contingent revenue under ASU 2014-09 to result in revenue being recognized earlier for certain contracts. In addition, ASU 2014-09 requires that all incremental costs of obtaining a contract with a customer be recognized as an asset. We expect this requirement will result in an increase in the costs that we capitalize. The guidance also requires that these costs be deferred over a term that is consistent with the transfer of services related to the asset. Based on our preliminary analysis, we believe this term will be approximately three years compared to one year or less under current guidance. Under ASU 2014-09, in addition to recording deferred revenue when the related cash payments are received for noncancellable services, we will record deferred revenue when payments are due in advance of our performance of those services. We expect this change will result in an offsetting increase in accounts receivable and deferred revenue. We are still evaluating the ASU for other potential impacts to our consolidated financial statements. We plan to adopt the guidance as of January 1, 2018 and expect to utilize the modified retrospective transition method. We plan to apply this transition method only to contracts that are not completed as of January 1, 2018. We have a project plan in place guiding our transition that includes the necessary changes to accounting processes, procedures, systems and internal controls. In May 2017, the FASB issued ASU 2017-09, Compensation – Stock Compensation (Topic 718): Scope of Modification Accounting. This ASU clarifies when to account for a change to the terms or conditions of a share-based payment award as a modification. Under the new guidance, modification accounting is required only if the fair value, the vesting conditions, or the classification of the award (as equity or liability) changes as a result of the change in terms or conditions. The ASU is effective prospectively for the annual period ending December 31, 2018 and interim periods within that annual period. Early adoption is permitted. The implementation of this standard is not expected to have a significant impact on our consolidated financial statements.
Fair Value of Financial Instruments	Cash equivalents primarily consist of AAA-rated money market funds with overnight liquidity and no stated maturities. We classified cash equivalents as Level 1 due to the short-term nature of these instruments and measured the fair value based on quoted prices in active markets for identical assets. When available, our marketable securities are valued using quoted prices for identical instruments in active markets. If we are unable to value our marketable securities using quoted prices for identical instruments in active markets, we value our investments using broker reports that utilize quoted market prices for comparable instruments. We validate, on a sample basis, the derived prices provided by the brokers by comparing their assessment of the fair values of our investments against the fair values of the portfolio balances of another third-party professional pricing service.
Stock-based Compensation	The fair value of each option grant and each share issued under the ESPP is estimated on the date of grant using the Black-Scholes option-pricing model. For stock options, expected volatility is based on the historical volatility of our common stock and historical volatilities for publicly traded stock of comparable companies over the estimated expected life of the options. For the ESPP purchase rights, expected volatility is based on the historical volatility of our common stock. The expected term represents the period of time the options and the ESPP purchase rights are expected to be outstanding. For stock options, the expected term is based on the “simplified method” as defined by SEC Staff Accounting Bulletin No. 110 (Topic 14.D.2). We use the “simplified method” due to the lack of sufficient historical exercise data to provide a reasonable basis upon which to otherwise estimate the expected life of the options. The expected term for the ESPP purchase rights approximates the offering period. The risk-free interest rate is based on yields on U.S. Treasury STRIPS (Separate Trading of Registered Interest and Principal of Securities) with a maturity similar to the estimated expected term of the options and ESPP purchase rights.

Organization and Significant Accounting Policies (Policies)

9 Months Ended

Sep. 30, 2017

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Basis of Presentation and Principles of Consolidation

The financial information presented in the accompanying unaudited condensed consolidated financial statements has been prepared in accordance with U.S. generally accepted accounting principles (“U.S. GAAP”) and in accordance with rules and regulations of the U.S. Securities and Exchange Commission (“SEC”) regarding interim financial reporting. Accordingly, the financial statements do not include all of the information and footnotes required by U.S. GAAP for complete financial statements. The condensed consolidated balance sheet data as of December 31, 2016 was derived from audited financial statements, but does not include all disclosures required by U.S. GAAP. In the opinion of management, the accompanying unaudited condensed consolidated financial statements reflect all adjustments, consisting primarily of normal recurring accruals, necessary for a fair presentation of our financial position and results of operations. The operating results for the three and nine months ended September 30, 2017 are not necessarily indicative of the results expected for the full year ending December 31, 2017.

Use of Estimates

The preparation of consolidated financial statements in conformity with U.S. GAAP requires us to make estimates and assumptions that affect the amounts reported in the consolidated financial statements and accompanying notes. We base our estimates on historical experience and various other assumptions believed to be reasonable. These estimates include, but are not limited to, the determination of the relative selling prices of our services, health insurance claims incurred but not yet reported, collectability of accounts receivable, valuation of available-for-sale marketable securities, useful lives of intangible assets and property and equipment, income taxes and certain assumptions used in the valuation of equity awards. While these estimates are based on our best knowledge of current events and actions that may affect us in the future, actual results may differ materially from these estimates.

Recently Adopted Accounting Pronouncements and New Accounting Pronouncements Not Yet Adopted

Recently Adopted Accounting Pronouncements

In March 2016, the FASB issued ASU 2016-09, Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting. Under this ASU, entities are permitted to make an accounting policy election to either estimate forfeitures on share-based payment awards, as required by current guidance, or to recognize forfeitures as they occur in addition to other changes. The guidance became effective for interim and annual periods beginning after December 15, 2016. Effective January 1, 2017, we adopted this standard. We elected to recognize forfeitures on share-based payment awards as they occur. The adoption, along with the remaining provisions of ASU 2016-09, did not have a material impact on our consolidated financial statements.

In October 2016, the FASB issued ASU 2016-16, Income Taxes - Intra-Entity Transfers of Assets Other Than Inventory, which requires entities to recognize the income tax consequences of an intra-entity transfer of an asset other than inventory when the transfer occurs. The new guidance is effective for annual reporting periods beginning after December 15, 2017. Early adoption is permitted as of the beginning of an annual reporting period. The new standard must be adopted using a modified retrospective transition method, with the cumulative effect recognized as of the date of initial adoption. Effective January 1, 2017, we adopted this standard. The adoption of this new guidance did not have a material impact on our consolidated financial statements.

New Accounting Pronouncements Not Yet Adopted

In May 2014, the Financial Accounting Standards Board (FASB) issued guidance codified in ASC 606, Revenue Recognition - Revenue from Contracts with Customers (ASU 2014-09), which amends the guidance in former ASC 605, Revenue Recognition. The core principle of ASU 2014-09 is that an entity should recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. Additionally, the guidance requires improved disclosures to help users of financial statements better understand the nature, amount, timing, and uncertainty of revenue and cash flows arising from contracts with customers. The FASB has issued several amendments and updates to the new revenue standard, including guidance related to when an entity should recognize revenue gross as a principal or net as an agent and how an entity should identify performance obligations. As amended, ASU 2014-09 is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2017. Early adoption is permitted for all entities only as of annual reporting periods beginning after December 15, 2016, including interim reporting periods within that reporting period.

We believe the adoption of ASU 2014-09 will require us to recognize revenue from certain of our professional services over time rather than upon completion of the services. We expect this change may result in some acceleration of revenue recognition.

We have determined that an agreement to purchase our professional services constitutes an option to purchase services in accordance with ASC 606-10-55-41 rather than an agreement that creates enforceable rights and obligations because of the customer’s contractual right to cancel the unused services. Based on our review, certain of our professional service agreements do not contain a material right and are only accounted for in accordance with ASU 2014-09 when the customer exercises its option to purchase additional goods or services. In the case of agreements where we have determined that the

option provides the customer with a material right, we will be required to allocate a portion of the transaction price to the material right. The treatment of customer options under ASU 2014-09 may result in a different allocation of the transaction price than under current guidance.

In addition, under current guidance, the amount that is allocated to, and recognized as revenue related to, a delivered service is limited to the amount that is not contingent on completion of the remaining performance obligations. We expect the removal of this limitation on contingent revenue under ASU 2014-09 to result in revenue being recognized earlier for certain contracts.

In addition, ASU 2014-09 requires that all incremental costs of obtaining a contract with a customer be recognized as an asset. We expect this requirement will result in an increase in the costs that we capitalize. The guidance also requires that these costs be deferred over a term that is consistent with the transfer of services related to the asset. Based on our preliminary analysis, we believe this term will be approximately three years compared to one year or less under current guidance.

Under ASU 2014-09, in addition to recording deferred revenue when the related cash payments are received for noncancellable services, we will record deferred revenue when payments are due in advance of our performance of those services. We expect this change will result in an offsetting increase in accounts receivable and deferred revenue.

We are still evaluating the ASU for other potential impacts to our consolidated financial statements. We plan to adopt the guidance as of January 1, 2018 and expect to utilize the modified retrospective transition method. We plan to apply this transition method only to contracts that are not completed as of January 1, 2018. We have a project plan in place guiding our transition that includes the necessary changes to accounting processes, procedures, systems and internal controls.

In May 2017, the FASB issued ASU 2017-09, Compensation – Stock Compensation (Topic 718): Scope of Modification Accounting. This ASU clarifies when to account for a change to the terms or conditions of a share-based payment award as a modification. Under the new guidance, modification accounting is required only if the fair value, the vesting conditions, or the classification of the award (as equity or liability) changes as a result of the change in terms or conditions. The ASU is effective prospectively for the annual period ending December 31, 2018 and interim periods within that annual period. Early adoption is permitted. The implementation of this standard is not expected to have a significant impact on our consolidated financial statements.

Fair Value of Financial Instruments

Cash equivalents primarily consist of AAA-rated money market funds with overnight liquidity and no stated maturities. We classified cash equivalents as Level 1 due to the short-term nature of these instruments and measured the fair value based on quoted prices in active markets for identical assets. When available, our marketable securities are valued using quoted prices for identical instruments in active markets. If we are unable to value our marketable securities using quoted prices for identical instruments in active markets, we value our investments using broker reports that utilize quoted market prices for comparable instruments. We validate, on a sample basis, the derived prices provided by the brokers by comparing their assessment of the fair values of our investments against the fair values of the portfolio balances of another third-party professional pricing service.

Stock-based Compensation

The fair value of each option grant and each share issued under the ESPP is estimated on the date of grant using the Black-Scholes option-pricing model. For stock options, expected volatility is based on the historical volatility of our common stock and historical volatilities for publicly traded stock of comparable companies over the estimated expected life of the options. For the ESPP purchase rights, expected volatility is based on the historical volatility of our common stock. The expected term represents the period of time the options and the ESPP purchase rights are expected to be outstanding. For stock options, the expected term is based on the “simplified method” as defined by SEC Staff Accounting Bulletin No. 110 (Topic 14.D.2). We use the “simplified method” due to the lack of sufficient historical exercise data to provide a reasonable basis upon which to otherwise estimate the expected life of the options. The expected term for the ESPP purchase rights approximates the offering period. The risk-free interest rate is based on yields on U.S. Treasury STRIPS (Separate Trading of Registered Interest and Principal of Securities) with a maturity similar to the estimated expected term of the options and ESPP purchase rights.