Accounting Policies, by Policy (Policies)	3 Months Ended	6 Months Ended
Sep. 30, 2014	Jun. 30, 2014
Accounting Policies [Abstract]
Use of Estimates, Policy [Policy Text Block]	Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the financial statements, and the reported amounts of revenues and expenses during the reporting period. Certain of the Company’s accounting policies require higher degrees of judgment than others in their application. These include the recognition of revenue and earnings from construction contracts under the percentage-of-completion method, the valuation of long-term assets (including goodwill), and income taxes. Management continually evaluates all of its estimates and judgments based on available information and experience; however, actual amounts could differ from those estimates.
Revenue Recognition, Percentage-of-Completion Method [Policy Text Block]	Construction Revenue Recognition The Company is a general contractor which engages in various types of heavy civil construction projects principally for public (government) owners. Credit risk is minimal with public owners since the Company ascertains that funds have been appropriated by the governmental project owner prior to commencing work on such projects. While most public contracts are subject to termination at the election of the government entity, in the event of termination, the Company is entitled to receive the contract price for completed work and reimbursement of termination-related costs. Credit risk with private owners is minimized because of statutory mechanics liens, which give the Company high priority in the event of lien foreclosures following financial difficulties of private owners. Revenues are recognized on the percentage-of-completion method, measured by the ratio of costs incurred up to a given date to estimated total costs for each contract. The Company’s contracts generally take 12 to 36 months to complete. Contract costs include all direct material, labor, subcontract and other costs and those indirect costs related to contract performance, such as indirect salaries and wages, equipment repairs and depreciation, insurance and payroll taxes. Administrative and general expenses are charged to expense as incurred. Provisions for estimated losses on uncompleted contracts are made in the period in which such losses are determined. Changes in job performance, job conditions and estimated profitability, including those changes arising from contract penalty provisions and final contract settlements may result in revisions to estimated costs, costs and income and are recognized in the period in which the revisions are determined. Changes in estimated revenues and gross margin during the three and nine months ended September 30, 2014 resulted in a net loss of $4.5 million and a net gain of $0.4 million, respectively, included in the operating results, or a loss of $0.24 and a gain of $0.02, respectively, per diluted share attributable to Sterling common stockholders.
Fair Value of Financial Instruments, Policy [Policy Text Block]		Financial Instruments The fair value of financial instruments is the amount at which the instrument could be exchanged in a current transaction between willing parties. The Company’s financial instruments are cash and cash equivalents, short-term investments, short-term and long-term contracts receivable, derivatives, accounts payable, mortgage and notes payable, a credit facility with Comerica Bank (“Credit Facility”), the buy/sell agreement related to certain noncontrolling owners’ interests in subsidiaries which was converted to a mandatorily redeemable long-term liability on December 30, 2013 and an earn-out liability related to the acquisition of J. Banicki Construction, Inc. (“JBC”). The recorded values of cash and cash equivalents, short-term investments, short-term contracts receivable and accounts payable approximate their fair values based on their short-term nature. The Company currently has one long-term contract receivable which is discounted at 4.25% and recorded at fair value. Interest earned related to the long-term contract receivable was $0.1 and $0.3 million for the three and nine months ended September 30, 2014, respectively. We consider the credit quality of the borrower to assess the appropriate discount rate to apply and continuously monitor the borrower’s credit quality. The recorded value of the Credit Facility debt approximates its fair value, as interest approximates market rates. Refer to Note 5 regarding the fair value of derivatives and Note 9 regarding the fair value of the earn-out liability, the change to the mandatorily redeemable long-term liability and the change in noncontrolling owners’ interests in subsidiaries. The Company had one mortgage outstanding at September 30, 2014 and December 31, 2013 with a remaining balance of $0.1 million and $0.2 million, respectively, for the periods. The mortgage was accruing interest at 3.50% at both September 30, 2014 and December 31, 2013 and contains pre-payment penalties. At September 30, 2014 and December 31, 2013, the fair value of the mortgage approximated book value. The Company also has long-term notes payable of $2.6 million related to machinery and equipment purchased which have payment terms ranging from 3 to 5 years and associated interest rates ranging from 3.12% to 6.29%. The fair value of the notes payable approximates their book value. The Company does not have any off-balance sheet financial instruments other than operating leases (refer to Note 14 of the Notes to Consolidated Financial Statements in the 2013 Form 10-K). In order to assess the fair value of the Company’s financial instruments, the Company uses the fair value hierarchy established by GAAP which prioritizes the inputs used in valuation techniques into the following three levels: Level 1 Inputs – Based upon quoted prices for identical assets in active markets that the Company has the ability to access at the measurement date. Level 2 Inputs – Based upon quoted prices (other than Level 1) in active markets for similar assets, quoted prices for identical or similar assets in markets that are not active, inputs other than quoted prices that are observable for the asset such as interest rates, yield curves, volatilities and default rates and inputs that are derived principally from or corroborated by observable market data. Level 3 Inputs – Based on unobservable inputs reflecting the Company’s own assumptions about the assumptions that market participants would use in pricing the asset based on the best information available. For each financial instrument, the Company uses the highest priority level input that is available in order to appropriately value that particular instrument. In certain instances, Level 1 inputs are not available and the Company must use Level 2 or Level 3 inputs. In these cases, the Company provides a description of the valuation techniques used and the inputs used in the fair value measurement.
New Accounting Pronouncements, Policy [Policy Text Block]	Recent Accounting Pronouncements In August 2014, the Financial Accounting Standards Board issued ASU 2014-14, “Presentation of Financial Statement – Going Concern.” The guidance, which is effective for annual reporting periods ending after December 15, 2016 and interim periods within annual periods beginning after December 15, 2016, requires management to evaluate whether there is substantial doubt about the entity’s ability to continue as a going concern and to provide related footnote disclosures. Early adoption is permitted. Although early adoption is permitted, the Company expects to adopt this guidance as required and does not expect a material impact to our financial statements. In May 2014, the Financial Accounting Standards Board issued ASU 2014-09, “Revenue from Contracts with Customers.” The guidance, which is effective for annual reporting periods beginning after December 15, 2016, defines the steps to recognize revenue for entities that have contracts with customers. Early adoption is not permitted. The Company has not determined the effect of this new guidance.

Accounting Policies, by Policy (Policies)

3 Months Ended

6 Months Ended

Sep. 30, 2014

Jun. 30, 2014

Use of Estimates, Policy [Policy Text Block]

Use of Estimates

The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the financial statements, and the reported amounts of revenues and expenses during the reporting period. Certain of the Company’s accounting policies require higher degrees of judgment than others in their application. These include the recognition of revenue and earnings from construction contracts under the percentage-of-completion method, the valuation of long-term assets (including goodwill), and income taxes. Management continually evaluates all of its estimates and judgments based on available information and experience; however, actual amounts could differ from those estimates.

Revenue Recognition, Percentage-of-Completion Method [Policy Text Block]

Construction Revenue Recognition

The Company is a general contractor which engages in various types of heavy civil construction projects principally for public (government) owners. Credit risk is minimal with public owners since the Company ascertains that funds have been appropriated by the governmental project owner prior to commencing work on such projects. While most public contracts are subject to termination at the election of the government entity, in the event of termination, the Company is entitled to receive the contract price for completed work and reimbursement of termination-related costs. Credit risk with private owners is minimized because of statutory mechanics liens, which give the Company high priority in the event of lien foreclosures following financial difficulties of private owners.

Revenues are recognized on the percentage-of-completion method, measured by the ratio of costs incurred up to a given date to estimated total costs for each contract. The Company’s contracts generally take 12 to 36 months to complete.

Contract costs include all direct material, labor, subcontract and other costs and those indirect costs related to contract performance, such as indirect salaries and wages, equipment repairs and depreciation, insurance and payroll taxes. Administrative and general expenses are charged to expense as incurred. Provisions for estimated losses on uncompleted contracts are made in the period in which such losses are determined. Changes in job performance, job conditions and estimated profitability, including those changes arising from contract penalty provisions and final contract settlements may result in revisions to estimated costs, costs and income and are recognized in the period in which the revisions are determined. Changes in estimated revenues and gross margin during the three and nine months ended September 30, 2014 resulted in a net loss of $4.5 million and a net gain of $0.4 million, respectively, included in the operating results, or a loss of $0.24 and a gain of $0.02, respectively, per diluted share attributable to Sterling common stockholders.

Fair Value of Financial Instruments, Policy [Policy Text Block]

Financial Instruments

The fair value of financial instruments is the amount at which the instrument could be exchanged in a current transaction between willing parties. The Company’s financial instruments are cash and cash equivalents, short-term investments, short-term and long-term contracts receivable, derivatives, accounts payable, mortgage and notes payable, a credit facility with Comerica Bank (“Credit Facility”), the buy/sell agreement related to certain noncontrolling owners’ interests in subsidiaries which was converted to a mandatorily redeemable long-term liability on December 30, 2013 and an earn-out liability related to the acquisition of J. Banicki Construction, Inc. (“JBC”).

The recorded values of cash and cash equivalents, short-term investments, short-term contracts receivable and accounts payable approximate their fair values based on their short-term nature. The Company currently has one long-term contract receivable which is discounted at 4.25% and recorded at fair value. Interest earned related to the long-term contract receivable was $0.1 and $0.3 million for the three and nine months ended September 30, 2014, respectively. We consider the credit quality of the borrower to assess the appropriate discount rate to apply and continuously monitor the borrower’s credit quality.

The recorded value of the Credit Facility debt approximates its fair value, as interest approximates market rates. Refer to Note 5 regarding the fair value of derivatives and Note 9 regarding the fair value of the earn-out liability, the change to the mandatorily redeemable long-term liability and the change in noncontrolling owners’ interests in subsidiaries. The Company had one mortgage outstanding at September 30, 2014 and December 31, 2013 with a remaining balance of $0.1 million and $0.2 million, respectively, for the periods. The mortgage was accruing interest at 3.50% at both September 30, 2014 and December 31, 2013 and contains pre-payment penalties. At September 30, 2014 and December 31, 2013, the fair value of the mortgage approximated book value. The Company also has long-term notes payable of $2.6 million related to machinery and equipment purchased which have payment terms ranging from 3 to 5 years and associated interest rates ranging from 3.12% to 6.29%. The fair value of the notes payable approximates their book value. The Company does not have any off-balance sheet financial instruments other than operating leases (refer to Note 14 of the Notes to Consolidated Financial Statements in the 2013 Form 10-K).

In order to assess the fair value of the Company’s financial instruments, the Company uses the fair value hierarchy established by GAAP which prioritizes the inputs used in valuation techniques into the following three levels:

Level 1 Inputs – Based upon quoted prices for identical assets in active markets that the Company has the ability to access at the measurement date.

Level 2 Inputs – Based upon quoted prices (other than Level 1) in active markets for similar assets, quoted prices for identical or similar assets in markets that are not active, inputs other than quoted prices that are observable for the asset such as interest rates, yield curves, volatilities and default rates and inputs that are derived principally from or corroborated by observable market data.

Level 3 Inputs – Based on unobservable inputs reflecting the Company’s own assumptions about the assumptions that market participants would use in pricing the asset based on the best information available.

For each financial instrument, the Company uses the highest priority level input that is available in order to appropriately value that particular instrument. In certain instances, Level 1 inputs are not available and the Company must use Level 2 or Level 3 inputs. In these cases, the Company provides a description of the valuation techniques used and the inputs used in the fair value measurement.

New Accounting Pronouncements, Policy [Policy Text Block]

Recent Accounting Pronouncements

In August 2014, the Financial Accounting Standards Board issued ASU 2014-14, “Presentation of Financial Statement – Going Concern.” The guidance, which is effective for annual reporting periods ending after December 15, 2016 and interim periods within annual periods beginning after December 15, 2016, requires management to evaluate whether there is substantial doubt about the entity’s ability to continue as a going concern and to provide related footnote disclosures. Early adoption is permitted. Although early adoption is permitted, the Company expects to adopt this guidance as required and does not expect a material impact to our financial statements.

In May 2014, the Financial Accounting Standards Board issued ASU 2014-09, “Revenue from Contracts with Customers.” The guidance, which is effective for annual reporting periods beginning after December 15, 2016, defines the steps to recognize revenue for entities that have contracts with customers. Early adoption is not permitted. The Company has not determined the effect of this new guidance.