Sterling Infrastructure (STRL) 10-Q 3 Aug 21 2021 Q2 Quarterly report Financial data

Cover Page

Cover Page - shares	6 Months Ended
	Jun. 30, 2021	Jul. 30, 2021
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Jun. 30, 2021
Document Transition Report	false
Entity File Number	1-31993
Entity Registrant Name	STERLING CONSTRUCTION COMPANY, INC.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	25-1655321
Entity Address, Address Line One	1800 Hughes Landing Blvd.
Entity Address, City or Town	The Woodlands
Entity Address, State or Province	TX
Entity Address, Postal Zip Code	77380
City Area Code	281
Local Phone Number	214-0777
Title of 12(b) Security	Common Stock, $0.01 par value per share
Trading Symbol	STRL
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		28,764,381
Entity Central Index Key	0000874238
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q2
Amendment Flag	false

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Income Statement [Abstract]
Revenues	$ 401,666	$ 400,038	$ 716,982	$ 696,726
Cost of revenues	(345,419)	(340,439)	(615,703)	(601,882)
Gross profit	56,247	59,599	101,279	94,844
General and administrative expense	(15,829)	(18,451)	(32,928)	(36,055)
Intangible asset amortization	(2,866)	(2,866)	(5,732)	(5,703)
Acquisition related costs	0	(139)	0	(612)
Other operating expense, net	(4,832)	(5,097)	(7,144)	(7,325)
Operating income	32,720	33,046	55,475	45,149
Interest income	12	24	26	123
Interest expense	(5,737)	(7,557)	(11,741)	(15,360)
Gain on extinguishment of debt, net	1,401	0	1,064	0
Income before income taxes	28,396	25,513	44,824	29,912
Income tax expense	(8,179)	(7,248)	(12,939)	(8,432)
Net income	20,217	18,265	31,885	21,480
Less: Net income attributable to noncontrolling interests	(161)	(55)	(1,274)	(155)
Net income attributable to Sterling common stockholders	$ 20,056	$ 18,210	$ 30,611	$ 21,325
Net income per share attributable to Sterling common stockholders:
Basic (in dollars per share)	$ 0.70	$ 0.65	$ 1.08	$ 0.77
Diluted (in dollars per share)	$ 0.69	$ 0.65	$ 1.06	$ 0.76
Weighted average common shares outstanding:
Basic (in shares)	28,582	27,941	28,433	27,794
Diluted (in shares)	29,054	27,957	28,878	27,887

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Statement of Comprehensive Income [Abstract]
Net income	$ 20,217	$ 18,265	$ 31,885	$ 21,480
Other comprehensive income, net of tax
Change in interest rate swap, net of tax	728	(53)	1,623	(7,114)
Total comprehensive income	20,945	18,212	33,508	14,366
Less: Comprehensive income attributable to noncontrolling interests	(161)	(55)	(1,274)	(155)
Comprehensive income attributable to Sterling common stockholders	$ 20,784	$ 18,157	$ 32,234	$ 14,211

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents ($30,006 and $26,122 related to variable interest entities (“VIEs”))	$ 93,630	$ 66,185
Accounts receivable ($26,778 and $25,789 related to VIEs)	211,529	177,424
Contract assets ($11,704 and $8,370 related to VIEs)	86,184	84,975
Receivables from and equity in construction joint ventures ($6,027 and $9,708 related to VIEs)	18,011	16,653
Other current assets ($3,188 and $1,493 related to VIEs)	24,738	16,306
Total current assets	434,092	361,543
Property and equipment, net ($9,539 and $6,010 related to VIEs)	142,015	126,668
Operating lease right-of-use assets, net ($4,279 and $4,213 related to VIEs)	16,609	16,515
Goodwill ($1,501 and $1,501 related to VIEs)	192,014	192,014
Other intangibles, net	239,155	244,887
Deferred tax asset, net	0	7,817
Other non-current assets, net	3,305	3,250
Total assets	1,027,190	952,694
Current liabilities:
Accounts payable ($26,209 and $19,505 related to VIEs)	137,934	95,201
Contract liabilities ($17,953 and $17,678 related to VIEs)	141,236	114,019
Current maturities of long-term debt ($6,793 and $6,793 related to VIEs)	23,186	77,434
Current portion of long-term lease obligations ($2,011 and $1,801 related to VIEs)	7,942	7,588
Accrued compensation ($3,608 and $2,141 related to VIEs)	27,134	18,013
Other current liabilities ($1,472 and $1,374 related to VIEs)	8,810	9,629
Total current liabilities	346,242	321,884
Long-term debt ($79 and $53 related to VIEs)	303,531	291,249
Long-term lease obligations ($2,268 and $2,412 related to VIEs)	8,783	8,958
Members’ interest subject to mandatory redemption and undistributed earnings	56,488	51,290
Deferred tax liability, net	3,956	0
Other long-term liabilities ($722 and $722 related to VIEs)	9,420	10,584
Total liabilities	728,420	683,965
Commitments and contingencies (Note 11)
Stockholders’ equity:
Common stock, par value $0.01 per share; 38,000 shares authorized, 28,638 and 28,279 shares issued, 28,638 and 28,184 shares outstanding	286	283
Additional paid in capital	253,467	256,423
Treasury stock, at cost: 0 and 95 shares	0	(1,445)
Retained earnings	47,884	17,273
Accumulated other comprehensive loss	(3,641)	(5,264)
Total Sterling stockholders’ equity	297,996	267,270
Noncontrolling interests	774	1,459
Total stockholders’ equity	298,770	268,729
Total liabilities and stockholders’ equity	$ 1,027,190	$ 952,694

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Cash and cash equivalents	$ 93,630	$ 66,185
Accounts receivable	211,529	177,424
Contract assets	86,184	84,975
Receivables from and equity in construction joint ventures	18,011	16,653
Other current assets	24,738	16,306
Property and equipment, net	142,015	126,668
Operating lease right-of-use assets	16,609	16,515
Goodwill	192,014	192,014
Accounts payable	137,934	95,201
Contract liabilities	141,236	114,019
Current maturities of long-term debt	23,186	77,434
Current portion of long-term lease obligations	7,942	7,588
Accrued compensation	27,134	18,013
Other current liabilities	8,810	9,629
Long term debt	303,531	291,249
Long-term lease obligations	8,783	8,958
Other long-term liabilities	$ 9,420	$ 10,584
Common stock, par value (in usd per share)	$ 0.01	$ 0.01
Common stock authorized (in shares)	38,000,000	38,000,000
Common stock issued (in shares)	28,638,000	28,279,000
Common stock outstanding (in shares)	28,638,000	28,184,000
Treasury stock (in shares)	0	95,000
Variable Interest Entity, Primary Beneficiary
Cash and cash equivalents	$ 30,006	$ 26,122
Accounts receivable	26,778	25,789
Contract assets	11,704	8,370
Receivables from and equity in construction joint ventures	6,027	9,708
Other current assets	3,188	1,493
Property and equipment, net	9,539	6,010
Operating lease right-of-use assets	4,279	4,213
Goodwill	1,501	1,501
Accounts payable	26,209	19,505
Contract liabilities	17,953	17,678
Current maturities of long-term debt	6,793	6,793
Current portion of long-term lease obligations	2,011	1,801
Accrued compensation	3,608	2,141
Other current liabilities	1,472	1,374
Long term debt	79	53
Long-term lease obligations	2,268	2,412
Other long-term liabilities	$ 722	$ 722

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Cash flows from operating activities:
Net income	$ 20,217	$ 18,265	$ 31,885	$ 21,480
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization			16,707	16,541
Amortization of debt issuance costs and non-cash interest			1,264	1,762
Gain on disposal of property and equipment			(437)	(598)
Gain on debt extinguishment, net	(1,401)	0	(1,064)	0
Deferred taxes	7,152	5,310	11,294	6,223
Stock-based compensation expense			3,850	6,196
Change in fair value of interest rate swap			(51)	272
Changes in operating assets and liabilities (Note 15)			28,044	451
Net cash provided by operating activities			91,492	52,327
Cash flows from investing activities:
Capital expenditures			(22,150)	(14,574)
Proceeds from sale of property and equipment			690	769
Net cash used in investing activities			(21,460)	(13,805)
Cash flows from financing activities:
Repayments of debt			(40,072)	(22,644)
Distributions to noncontrolling interest owners			(1,959)	0
Other			(602)	9,067
Net cash used in financing activities			(42,633)	(13,577)
Net change in cash, cash equivalents, and restricted cash			27,399	24,945
Cash, cash equivalents, and restricted cash at beginning of period			72,642	50,562
Cash, cash equivalents, and restricted cash at end of period	100,041	75,507	100,041	75,507
Less: restricted cash (Other current assets)	(6,411)	(4,895)	(6,411)	(4,895)
Cash and cash equivalents at end of period	$ 93,630	$ 70,612	93,630	70,612
Non-cash items:
Capital expenditures			$ 4,425	$ 0

Condensed Consolidated Statem_4

Condensed Consolidated Statements of Changes in Stockholders' Equity - USD ($) shares in Thousands, $ in Thousands	Total	Total Sterling Stockholders’ Equity	Common Stock	Additional Paid in Capital	Treasury Stock	Retained Earnings (Deficit)	Accumulated Other Comprehensive Loss	Non-controlling Interests
Beginning balance (in shares) at Dec. 31, 2019			27,772		518
Beginning balance at Dec. 31, 2019	$ 221,211	$ 219,918	$ 283	$ 251,019	$ (6,142)	$ (25,033)	$ (209)	$ 1,293
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	3,215	3,115				3,115		100
Change in interest rate swap	(7,061)	(7,061)					(7,061)
Stock-based compensation	2,234	2,234		2,234
Issuance of stock (in shares)			248		248
Issuance of stock	103	103		(2,460)	$ 2,563
Shares withheld for taxes (in shares)			54		46
Shares withheld for taxes	(772)	(772)		(104)	$ (668)
Ending balance (in shares) at Mar. 31, 2020			27,966		316
Ending balance at Mar. 31, 2020	218,930	217,537	$ 283	250,689	$ (4,247)	(21,918)	(7,270)	1,393
Beginning balance (in shares) at Dec. 31, 2019			27,772		518
Beginning balance at Dec. 31, 2019	221,211	219,918	$ 283	251,019	$ (6,142)	(25,033)	(209)	1,293
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	21,480
Change in interest rate swap	(7,114)
Ending balance (in shares) at Jun. 30, 2020			28,034		246
Ending balance at Jun. 30, 2020	241,085	239,637	$ 283	253,820	$ (3,435)	(3,708)	(7,323)	1,448
Beginning balance (in shares) at Mar. 31, 2020			27,966		316
Beginning balance at Mar. 31, 2020	218,930	217,537	$ 283	250,689	$ (4,247)	(21,918)	(7,270)	1,393
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	18,265	18,210				18,210		55
Change in interest rate swap	(53)	(53)					(53)
Stock-based compensation	3,962	3,962		3,962
Issuance of stock (in shares)			73		73
Issuance of stock	104	104		(740)	$ 844
Shares withheld for taxes (in shares)			5		3
Shares withheld for taxes	(50)	(50)		(18)	$ (32)
Other	(73)	(73)		(73)
Ending balance (in shares) at Jun. 30, 2020			28,034		246
Ending balance at Jun. 30, 2020	241,085	239,637	$ 283	253,820	$ (3,435)	(3,708)	(7,323)	1,448
Beginning balance (in shares) at Dec. 31, 2020			28,184		95
Beginning balance at Dec. 31, 2020	268,729	267,270	$ 283	256,423	$ (1,445)	17,273	(5,264)	1,459
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	11,668	10,555				10,555		1,113
Change in interest rate swap	895	895					895
Stock-based compensation	1,835	1,835		1,835
Distributions to owners	(1,959)	0						(1,959)
Issuance of stock (in shares)			668		111
Issuance of stock	144	144	$ 5	(1,602)	$ 1,741
Shares withheld for taxes (in shares)			246		16
Shares withheld for taxes	(5,619)	(5,619)	$ (2)	(5,321)	$ (296)
Ending balance (in shares) at Mar. 31, 2021			28,606		0
Ending balance at Mar. 31, 2021	275,693	275,080	$ 286	251,335	$ 0	27,828	(4,369)	613
Beginning balance (in shares) at Dec. 31, 2020			28,184		95
Beginning balance at Dec. 31, 2020	268,729	267,270	$ 283	256,423	$ (1,445)	17,273	(5,264)	1,459
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	31,885
Change in interest rate swap	1,623
Ending balance (in shares) at Jun. 30, 2021			28,638		0
Ending balance at Jun. 30, 2021	298,770	297,996	$ 286	253,467	$ 0	47,884	(3,641)	774
Beginning balance (in shares) at Mar. 31, 2021			28,606		0
Beginning balance at Mar. 31, 2021	275,693	275,080	$ 286	251,335	$ 0	27,828	(4,369)	613
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	20,217	20,056				20,056		161
Change in interest rate swap	728	728					728
Stock-based compensation	2,015	2,015		2,015
Issuance of stock (in shares)			32
Issuance of stock	120	120		120
Other	(3)	(3)		(3)
Ending balance (in shares) at Jun. 30, 2021			28,638		0
Ending balance at Jun. 30, 2021	$ 298,770	$ 297,996	$ 286	$ 253,467	$ 0	$ 47,884	$ (3,641)	$ 774

Nature of Operations

Nature of Operations	6 Months Ended
	Jun. 30, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Nature of Operations	1. NATURE OF OPERATIONS Business Summary

Basis of Presentation and Signi

Basis of Presentation and Significant Accounting Policies	6 Months Ended
	Jun. 30, 2021
Accounting Policies [Abstract]
Basis of Presentation and Significant Accounting Policies	2. BASIS OF PRESENTATION AND SIGNIFICANT ACCOUNTING POLICIES Basis of Presentation Presentation Basis— The accompanying Condensed Consolidated Financial Statements are presented in accordance with accounting policies generally accepted in the United States (“GAAP”) and reflect all wholly owned subsidiaries and those entities the Company is required to consolidate. See Note 4 - Consolidated 50% Owned Subsidiaries and Note 5 - Construction Joint Ventures for further discussion of the Company’s consolidation policy for those entities that are not wholly owned. In the opinion of management, all adjustments, consisting only of normal recurring adjustments, considered necessary for a fair presentation have been included. All significant intercompany accounts and transactions have been eliminated in consolidation. Values presented within tables (excluding per share data) are in thousands. Reclassifications have been made to historical financial data in the Condensed Consolidated Financial Statements to conform to the current year presentation. Estimates and Judgments— The preparation of the accompanying Condensed Consolidated Financial Statements in conformance with GAAP requires management to make estimates and judgments 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 accounting estimates of the Company require a higher degree of judgment than others in their application. These include the recognition of revenue and earnings from construction contracts over time, the valuation of long-lived assets, goodwill and purchase accounting estimates. Management continually evaluates all of its estimates and judgments based on available information and experience; however, actual results could differ from these estimates. Significant Accounting Policies Consistent with Regulation S-X Rule 10-1(a), the Company has omitted significant accounting policies in this quarterly report that would duplicate the disclosures contained in the Company’s annual report on Form 10-K for the year ended December 31, 2020 under “Part II, Item 8. - Notes to Consolidated Financial Statements.” This quarterly report should be read in conjunction with the Company’s most recent annual report on Form 10-K. Accounts Receivable— Receivables are generally based on amounts billed to the customer in accordance with contractual provisions. Receivables are written off based on the individual credit evaluation and specific circumstances of the customer, when such treatment is warranted. The Company performs a review of outstanding receivables, historical collection information and existing economic conditions to determine if there are potential uncollectible receivables. At June 30, 2021 and December 31, 2020, our allowance for our estimate of expected credit losses was zero. As is customary, we have agreed to indemnify our bonding company for all losses incurred by it in connection with bonds that are issued, and we have granted our bonding company a security interest in certain assets, including accounts receivable, as collateral for such obligations. Contracts in Progress— For performance obligations satisfied over time, amounts are billed as work progresses in accordance with agreed-upon contractual terms, either at periodic intervals (e.g., biweekly or monthly) or upon achievement of contractual milestones. Typically, Sterling bills for advances or deposits from its customers before revenue is recognized, resulting in contract liabilities. However, the Company occasionally bills subsequent to revenue recognition, resulting in contract assets. Many of the contracts under which the Company performs work also contain retainage provisions. Retainage refers to that portion of our billings held for payment by the customer pending satisfactory completion of the project. Unless reserved, the Company assumes that all amounts retained by customers under such provisions are fully collectible. At June 30, 2021 and December 31, 2020, contract assets included $45,924 and $44,412 of retainage, respectively, and contract liabilities included $39,682 and $33,856 of retainage, respectively. Retainage on active contracts is classified as current regardless of the term of the contract and is generally collected within one year of the completion of a contract. We anticipate collecting approximately 68% of our June 30, 2021 retainage during the next twelve months. These assets and liabilities are reported on the Condensed Consolidated Balance Sheet within “Contract assets” and “Contract liabilities” on a contract-by-contract basis at the end of each reporting period. Revenue recognized for the three and six months ended June 30, 2021 that was included in the contract liability balance on December 31, 2020 was $141,813 and $297,370, respectively. Revenue recognized for the three and six months ended June 30, 2020 that was included in the contract liability balance on December 31, 2019 was $132,225 and $278,491, respectively. Cash and Restricted Cash— Our cash is comprised of highly liquid investments with maturities of three months or less. Restricted cash of $6,411 and $6,457 is included in “Other current assets” on the Condensed Consolidated Balance Sheets at June 30, 2021 and December 31, 2020, respectively. This primarily represents cash deposited by the Company into separate accounts and designated as collateral for standby letters of credit in the same amount in accordance with contractual agreements.

Revenue From Customers

Revenue From Customers	6 Months Ended
	Jun. 30, 2021
Revenue from Contract with Customer [Abstract]
Revenue From Customers	3. REVENUE FROM CUSTOMERS Backlog — The following table presents the Company’s backlog, by segment: June 30, December 31, Heavy Civil Backlog $ 1,183,122 $ 898,183 Specialty Services Backlog 387,519 277,205 Total Heavy Civil and Specialty Services Backlog $ 1,570,641 $ 1,175,388 The Company expects to recognize approximately 59% of its backlog as revenue during the next twelve months, and the balance thereafter. Revenue Disaggregation — The following tables present the Company’s revenue disaggregated by major end market and contract type: Three Months Ended June 30, Six Months Ended June 30, Revenues by major end market 2021 2020 2021 2020 Heavy Highway $ 139,189 $ 152,526 $ 238,705 $ 248,900 Aviation 36,754 34,867 63,976 63,324 Water Containment and Treatment 16,208 16,529 30,427 38,338 Other 11,002 16,526 17,099 25,501 Heavy Civil Revenues 203,153 220,448 350,207 376,063 Land Development 123,743 105,639 220,315 181,884 Commercial 28,161 30,064 55,677 58,542 Specialty Services Revenues 151,904 135,703 275,992 240,426 Residential Revenues 46,609 43,887 90,783 80,237 Total Revenues $ 401,666 $ 400,038 $ 716,982 $ 696,726 Revenues by contract type Fixed-Unit Price $ 225,886 $ 203,692 $ 403,434 $ 345,431 Lump Sum 127,416 147,460 218,571 261,712 Residential and Other 48,364 48,886 94,977 89,583 Total Revenues $ 401,666 $ 400,038 $ 716,982 $ 696,726 Each of these contract types presents advantages and disadvantages. Typically, the Company assumes more risk with lump-sum contracts. However, these types of contracts offer additional profits if the work is completed for less than originally estimated. Under fixed-unit price contracts, the Company’s profit may vary if actual labor-hour costs vary significantly from the negotiated rates. Also, because some contracts can provide little or no fee for managing material costs, the components of contract cost can impact profitability. Variable Consideration The Company has projects that it is in the process of negotiating, or awaiting final approval of, unapproved change orders and claims with its customers. The Company is proceeding with its contractual rights to recoup additional costs incurred from its customers based on completing work associated with change orders, including change orders with pending change order pricing, or claims related to significant changes in scope which resulted in substantial delays and additional costs in completing the work. Unapproved change order and claim information has been provided to the Company’s customers and negotiations with the customers are ongoing. If additional progress with an acceptable resolution is not reached, legal action will be taken. Based upon the Company’s review of the provisions of its contracts, specific costs incurred and other related evidence supporting the unapproved change orders and claims, together in some cases as necessary with the views of the Company’s outside claim consultants, the Company concluded it was appropriate to include in project price amounts of $14,300 and $7,142, at June 30, 2021 and December 31, 2020, respectively, relating to unapproved change orders and claims. Provisions for estimated losses on uncompleted contracts are made in the period in which such losses are determined. Contract Estimates Accounting for long-term contracts and programs involves the use of various techniques to estimate total contract revenue and costs. For long-term contracts, the Company estimates the profit on a contract as the difference between the total estimated revenue and expected costs to complete a contract and recognizes such profit over the life of the contract. Contract estimates are based on various assumptions to project the outcome of future events that often span several years. These assumptions include labor productivity and availability, the complexity of the work to be performed, the cost and availability of materials and the performance of subcontractors. 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 costs and income and are recognized in the period in which the revisions are determined. Changes in contract estimates resulted in net increases of approximately $3,727 and $12,032 for the three and six months ended June 30, 2021, and net increases of approximately $2,197 and $2,292 for the three and six months ended June 30, 2020, included in “Operating income” on the Condensed Consolidated Statements of Operations.

Consolidated 50% Owned Subsidia

Consolidated 50% Owned Subsidiaries	6 Months Ended
	Jun. 30, 2021
Noncontrolling Interest [Abstract]
Consolidated 50% Owned Subsidiaries	4. CONSOLIDATED 50% OWNED SUBSIDIARIES The Company has 50% ownership interests in two subsidiaries (“Myers” and “RHB”) that it fully consolidates as a result of its exercise of control over the entities. The earnings attributable to the 50% portions the Company does not own were approximately $4,800 and $6,600 for the three and six months ended June 30, 2021, respectively, and $4,600 and $6,300 for the three and six months ended June 30, 2020, respectively, and are eliminated within “Other operating expense, net” in the Condensed Consolidated Statements of Operations. Any undistributed earnings for partners are included in “Members’ interest subject to mandatory redemption and undistributed earnings” within the Condensed Consolidated Balance Sheets and are mandatorily payable at the time of the noncontrolling owners’ death or permanent disability. These two subsidiaries have individual mandatory redemption provisions which, under circumstances outlined in the partner agreements, are certain to occur and obligate the Company to purchase each partner’s remaining 50% interests for $20,000 ($40,000 in the aggregate). The Company has purchased two separate $20,000 death and permanent total disability insurance policies to mitigate the Company’s cash draw if such events were to occur. These purchase obligations are also recorded in “Members’ interest subject to mandatory redemption and undistributed earnings” on the Condensed Consolidated Balance Sheets. The liability consists of the following: June 30, December 31, Members’ interest subject to mandatory redemption $ 40,000 $ 40,000 Net accumulated earnings 16,488 11,290 Total liability $ 56,488 $ 51,290 The Company must determine whether any of its entities, including these two 50% owned subsidiaries, in which it participates, is a VIE. The Company determined that Myers is a VIE and that the Company is the primary beneficiary because, pursuant to the terms of the Myers Operating Agreement, the Company is exposed to the majority of potential losses of the partnership. Summary financial information for Myers is as follows: Three Months Ended June 30, Six Months Ended June 30, 2021 2020 2021 2020 Revenues $ 43,137 $ 54,364 $ 71,094 $ 98,726 Operating income $ 747 $ 1,049 $ 1,465 $ 1,204 Net income $ 366 $ 526 $ 717 $ 605

Construction Joint Ventures

Construction Joint Ventures	6 Months Ended
	Jun. 30, 2021
Equity Method Investments and Joint Ventures [Abstract]
Construction Joint Ventures	5. CONSTRUCTION JOINT VENTURES Joint Ventures with a Controlling Interest —We consolidate any venture that is determined to be a VIE for which we are the primary beneficiary, or which we otherwise effectively control. The equity held by the remaining owners and their portions of net income (loss) are reflected in stockholders’ equity on the Condensed Consolidated Balance Sheets line item “Noncontrolling interests” and in the Condensed Consolidated Statements of Operations line item “Net income attributable to noncontrolling interests,” respectively. The Company determined that a joint venture in which the Company’s Ralph L. Wadsworth Construction subsidiary is a 51% owner is a VIE and the Company is the primary beneficiary. Summary financial information for this construction joint venture is as follows: Three Months Ended June 30, Six Months Ended June 30, 2021 2020 2021 2020 Revenues $ 9,325 $ 3,404 $ 17,566 $ 7,468 Operating income $ 613 $ 375 $ 3,140 $ 671 Net income $ 615 $ 376 $ 3,143 $ 675 Joint Ventures with a Noncontrolling Interest —The Company accounts for unconsolidated joint ventures using a pro-rata basis in the Condensed Consolidated Statements of Operations and as a single line item (“Receivables from and equity in construction joint ventures”) in the Condensed Consolidated Balance Sheets. This method is a permissible modification of the equity method of accounting which is a common practice in the construction industry. Combined financial amounts of joint ventures in which the Company has a noncontrolling interest and the Company’s share of such amounts which are included in the Company’s Condensed Consolidated Financial Statements are shown below: June 30, December 31, Current assets $ 138,804 $ 143,608 Current liabilities $ (95,350) $ (141,295) Sterling’s receivables from and equity in construction joint ventures $ 18,011 $ 16,653 Three Months Ended June 30, Six Months Ended June 30, 2021 2020 2021 2020 Revenues $ 62,489 $ 43,466 $ 111,906 $ 70,312 Income before tax $ 8,780 $ 4,516 $ 13,415 $ 6,673 Sterling’s noncontrolling interest: Revenues $ 26,994 $ 19,377 $ 48,938 $ 32,459 Income before tax $ 3,676 $ 1,968 $ 5,811 $ 3,017 The caption “Receivables from and equity in construction joint ventures” includes undistributed earnings and receivables owed to the Company. Undistributed earnings are typically released to the joint venture partners after the customer accepts the project as completed and the warranty period, if any, has passed. Other —The use of joint ventures exposes us to a number of risks, including the risk that our partners may be unable or unwilling to provide their share of capital investment to fund the operations of the venture or complete their obligations to us, the venture, or ultimately, the customer. Differences in opinions or views among joint venture partners could also result in delayed decision-making or failure to agree on material issues, which could adversely affect the business and operations of the joint venture. In addition, agreement terms may subject us to joint and several liability for our venture partners, and the failure of our venture partners to perform their obligations could impose additional performance and financial obligations on us. The aforementioned factors could result in unanticipated costs to complete the projects, liquidated damages or contract disputes, including claims against our partners.

Property and Equipment

Property and Equipment	6 Months Ended
	Jun. 30, 2021
Property, Plant and Equipment [Abstract]
Property and Equipment	6. PROPERTY AND EQUIPMENT Property and equipment are summarized as follows: June 30, December 31, Construction and transportation equipment $ 252,797 $ 231,799 Buildings and improvements 22,493 21,025 Land 3,891 3,891 Office equipment 3,046 3,012 Total property and equipment 282,227 259,727 Less accumulated depreciation (140,212) (133,059) Total property and equipment, net $ 142,015 $ 126,668 Depreciation Expense— Depreciation expense is primarily included within cost of revenues and was $5,536 and $10,975 for the three and six months ended June 30, 2021, respectively, and $5,390 and $10,838 for the three and six months ended June 30, 2020, respectively.

Other Intangible Assets

Other Intangible Assets	6 Months Ended
	Jun. 30, 2021
Goodwill and Intangible Assets Disclosure [Abstract]
Other Intangible Assets	7. OTHER INTANGIBLE ASSETS The following table presents our acquired finite-lived intangible assets, including the weighted-average useful lives for each major intangible asset category and in total: June 30, 2021 December 31, 2020 Weighted Gross Accumulated Gross Accumulated Customer relationships 25 $ 232,623 $ (21,099) $ 232,623 $ (16,360) Trade name 23 30,107 (3,967) 30,107 (3,209) Non-compete agreements 5 2,487 (996) 2,487 (761) Total 24 $ 265,217 $ (26,062) $ 265,217 $ (20,330) The Company's intangible amortization expense was $2,866 and $5,732 for the three and six months ended June 30, 2021, respectively, and $2,866 and $5,703 for the three and six months ended June 30, 2020, respectively.

Debt

Debt	6 Months Ended
	Jun. 30, 2021
Debt Disclosure [Abstract]
Debt	8. DEBT The Company’s outstanding debt was as follows: June 30, December 31, Term Loan Facility $ 315,000 $ 355,000 Revolving Credit Facility — — Credit Facility 315,000 355,000 Other debt 17,335 20,397 Total debt 332,335 375,397 Less - Current maturities of long-term debt (23,186) (77,434) Less - Unamortized debt issuance costs (5,618) (6,714) Total long-term debt $ 303,531 $ 291,249 Credit Facility —Our amended credit agreement (the “Credit Agreement”) provides the Company with senior secured debt financing in an amount up to $475,000 in the aggregate, consisting of (i) a senior secured first lien term loan facility (the “Term Loan Facility”) in the amount of $400,000 (collectively, the “Credit Facility”) and (ii) a senior secured first lien revolving credit facility (the “Revolving Credit Facility”) in an aggregate principal amount of $75,000 (with a $75,000 limit for the issuance of letters of credit and a $15,000 sublimit for swing line loans). The obligations under the Credit Facility are secured by substantially all assets of the Company and the subsidiary guarantors, subject to certain permitted liens and interests of other parties. The Credit Facility will mature on October 2, 2024. On June 28, 2021, the Credit Agreement was further amended to (i) decrease the applicable margins with respect to the rates per annum applicable to Base Rate Loans (as defined in the Credit Agreement), Eurodollar Loans (as defined in the Credit Agreement), Letter of Credit (as defined in the Credit Agreement) fees and the commitment fee payable under the Revolving Credit Facility and Term Loan Facility; (ii) reduce the applicable percentages of excess cash flow required for application to mandatory prepayments of the Credit Facility; and (iii) decrease the amounts of the scheduled quarterly principal payments due under the Term Loan Facility. The Term Loan Facility bears interest at either the base rate plus a margin, or at a one-, two-, three-, six- or, if available, twelve-month LIBOR rate plus a margin, at the Company’s election. At June 30, 2021, the Company calculated interest using a one-month LIBOR rate and an applicable margin of 0.095% and 2.50% per annum, respectively. We continue to utilize an interest rate swap to hedge against $275,000 of the outstanding Term Loan Facility, which resulted in a weighted average interest rate of approximately 5.49% per annum during the six months ended June 30, 2021. Scheduled principal payments on the Term Loan Facility are made quarterly and total $24,700, $16,200, $22,300 and $18,300 for each of the years ending 2021, 2022, 2023 and 2024, respectively. The Company is required to make mandatory prepayments on the Credit Facility with proceeds received from issuances of debt, events of loss and certain dispositions. The Company also is required to prepay the Credit Facility with its excess cash flow within 5 days after receipt of its annual audited financial statements. For the six months ended June 30, 2021, the company made scheduled term loan payments of $16,556, an excess cash flow payment of $18,000 and an optional prepayment of $5,444. A final payment of all principal and interest then outstanding on the Term Loan Facility is due on October 2, 2024. The Revolving Credit Facility bears interest at the same rate options as the Term Loan Facility. In addition to interest on debt borrowings, we are assessed quarterly commitment fees on the unutilized portion of the facility as well as letter of credit fees on outstanding instruments. At June 30, 2021, we had no outstanding borrowings under the Revolving Credit Facility, providing $75,000 of available capacity. Debt Issuance Costs —The costs associated with the Term Loan Facility and Revolving Credit Facility are reflected on the Condensed Consolidated Balance Sheets as a direct reduction from the related debt liability and amortized over the terms of the respective facilities. Amortization of debt issuance costs was $604 and $1,264 for the three and six months ended June 30, 2021, respectively, and $740 and $1,492 for the three and six months ended June 30, 2020, respectively, and was recorded as interest expense. Additionally, due to early payments of $18,000 and $5,444 on the Term Loan Facility in the first and second quarters of 2021, respectively, we recorded losses on debt extinguishment of $94 and $431 for the three and six months ended June 30, 2020, respectively, related to debt issuance costs. Other Debt —During the second quarter of 2020, the Company’s two 50% owned subsidiaries received three short-term Paycheck Protection Program loans (the “PPP Loans”) totaling approximately $9,800. During the second quarter of 2021, the Small Business Administration (“SBA”) forgave one of the PPP Loans of approximately $3,000, of which the Company recorded a gain on debt extinguishment of $1,495 for its 50% portion of the gain. The remaining two PPP Loans are classified as short-term debt under “Current Liabilities” on the Consolidated Balance Sheets at June 30, 2021, as we expect to receive a forgiveness determination by the SBA within the next twelve months. Compliance and Other —The Credit Agreement contains various affirmative and negative covenants that may, subject to certain exceptions, restrict the ability of us and our subsidiaries to, among other things, grant liens, incur additional indebtedness, make loans, advances or other investments, make non-ordinary course asset sales, declare or pay dividends or make other distributions with respect to equity interests, purchase, redeem or otherwise acquire or retire capital stock or other equity interests, or merge or consolidate with any other person, among various other things. In addition, the Company is required to maintain certain financial covenants. As of June 30, 2021, we were in compliance with all of our restrictive and financial covenants. The Company’s debt is recorded at its carrying amount in the Condensed Consolidated Balance Sheets. At June 30, 2021 and December 31, 2020, the carrying values of our debt outstanding approximated the fair values.

Financial Instruments

Financial Instruments	6 Months Ended
	Jun. 30, 2021
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Financial Instruments	9. FINANCIAL INSTRUMENTS Interest Rate Derivative —We continue to utilize a swap arrangement to hedge against interest rate variability associated with $275,000 of the $315,000 outstanding under the Term Loan Facility. The Company has designated its interest rate swap agreement as a cash flow hedging derivative. To the extent the derivative instrument is effective and the documentation requirements have been met, changes in fair value are recognized in other comprehensive income (loss) (“OCI”) until the underlying hedged item is recognized in earnings. At June 30, 2021, the fair value of the swap recorded in accumulated other comprehensive income (loss) (“AOCI”) was a net loss of $4,719. Derivatives Disclosures Fair Value —Financial instruments are required to be categorized within a valuation hierarchy based upon the lowest level of input that is significant to the fair value measurement. The three levels of the valuation hierarchy are as follows: • Level 1—Fair value is based on quoted prices in active markets. • Level 2—Fair value is based on internally developed models that use, as their basis, readily observable market parameters. Our derivative positions are classified within level 2 of the valuation hierarchy as they are valued using quoted market prices for similar assets and liabilities in active markets. These level 2 derivatives are valued utilizing an income approach, which discounts future cash flow based on current market expectations and adjusts for credit risk. • Level 3—Fair value is based on internally developed models that use, as their basis, significant unobservable market parameters. The Company did not have any level 3 classifications at June 30, 2021 or December 31, 2020. The following table presents the fair value of the interest rate derivative by valuation hierarchy and balance sheet classification: June 30, 2021 December 31, 2020 Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Total Other current liabilities $ — $ (3,794) $ — $ (3,794) $ — $ (4,427) $ — $ (4,427) Other non-current liabilities — (1,108) — (1,108) — (2,629) — (2,629) Total liabilities at fair value $ — $ (4,902) $ — $ (4,902) $ — $ (7,056) $ — $ (7,056) OCI —The following table presents the total value recognized in OCI and reclassified from AOCI into earnings during the three and six months ended June 30, 2021 and 2020 for derivatives designated as cash flow hedges: Three Months Ended June 30, 2021 Six Months Ended June 30, 2021 Before Tax Tax Net of Tax Before Tax Tax Net of Tax Net gain (loss) recognized in OCI $ (82) $ 19 $ (63) $ 44 $ (10) $ 34 Net amount reclassified from AOCI into earnings (1) 1,024 (233) 791 2,058 (469) 1,589 Change in other comprehensive income $ 942 $ (214) $ 728 $ 2,102 $ (479) $ 1,623 Three Months Ended June 30, 2020 Six Months Ended June 30, 2020 Before Tax Tax Net of Tax Before Tax Tax Net of Tax Net gain (loss) recognized in OCI $ (1,031) $ 232 $ (799) $ (10,205) $ 2,296 $ (7,909) Net amount reclassified from AOCI into earnings 963 (217) 746 1,026 (231) 795 Change in other comprehensive income $ (68) $ 15 $ (53) $ (9,179) $ 2,065 $ (7,114) (1) Net unrealized losses totaling $3,611 are anticipated to be reclassified from AOCI into earnings during the next 12 months due to settlement of the associated underlying obligations.

Lease Obligations

Lease Obligations	6 Months Ended
	Jun. 30, 2021
Leases [Abstract]
Lease Obligations	10. LEASE OBLIGATIONS The Company has operating and finance leases primarily for construction and transportation equipment, as well as office space. The Company’s leases have remaining lease terms of one month to seven years, some of which include options to extend the leases for up to ten years. The components of lease expense are as follows: Three Months Ended June 30, Six Months Ended June 30, 2021 2020 2021 2020 Operating lease cost $ 1,510 $ 2,075 $ 3,022 $ 4,234 Short-term lease cost $ 2,911 $ 3,745 $ 5,035 $ 7,026 Finance lease cost: Amortization of right-of-use assets $ 46 $ 49 $ 96 $ 105 Interest on lease liabilities 5 7 11 15 Total finance lease cost $ 51 $ 56 $ 107 $ 120 Supplemental cash flow information related to leases is as follows: Six Months Ended June 30, 2021 2020 Cash paid for amounts included in the measurement of lease liabilities: Operating cash flows from operating leases $ 2,980 $ 4,336 Operating cash flows from finance leases $ 11 $ 15 Financing cash flows from finance leases $ 96 $ 105 Right-of-use assets obtained in exchange for lease obligations (noncash): Operating leases $ 3,496 $ 5,633 Finance leases $ — $ — Supplemental balance sheet information related to leases is as follows: June 30, December 31, Operating Leases Operating lease right-of-use assets $ 16,609 $ 16,515 Current portion of long-term lease obligations $ 7,942 $ 7,588 Long-term lease obligations 8,783 8,958 Total operating lease liabilities $ 16,725 $ 16,546 Finance Leases Property and equipment, at cost $ 1,479 $ 1,479 Accumulated depreciation (806) (702) Property and equipment, net $ 673 $ 777 Current maturities of long-term debt $ 168 $ 188 Long-term debt 295 372 Total finance lease liabilities $ 463 $ 560 Weighted Average Remaining Lease Term Operating leases 3.4 3.2 Finance leases 2.9 3.2 Weighted Average Discount Rate Operating leases 5.5 % 5.7 % Finance leases 4.2 % 4.2 % Maturities of lease liabilities are as follows: Operating Finance Year Ending December 31, 2021 (excluding the six months ended June 30, 2021) $ 3,715 $ 101 2022 6,510 161 2023 3,866 154 2024 1,820 77 2025 1,002 — 2026 928 — Thereafter 628 — Total lease payments $ 18,469 $ 493 Less imputed interest (1,744) (30) Total $ 16,725 $ 463
Lease Obligations	10. LEASE OBLIGATIONS The Company has operating and finance leases primarily for construction and transportation equipment, as well as office space. The Company’s leases have remaining lease terms of one month to seven years, some of which include options to extend the leases for up to ten years. The components of lease expense are as follows: Three Months Ended June 30, Six Months Ended June 30, 2021 2020 2021 2020 Operating lease cost $ 1,510 $ 2,075 $ 3,022 $ 4,234 Short-term lease cost $ 2,911 $ 3,745 $ 5,035 $ 7,026 Finance lease cost: Amortization of right-of-use assets $ 46 $ 49 $ 96 $ 105 Interest on lease liabilities 5 7 11 15 Total finance lease cost $ 51 $ 56 $ 107 $ 120 Supplemental cash flow information related to leases is as follows: Six Months Ended June 30, 2021 2020 Cash paid for amounts included in the measurement of lease liabilities: Operating cash flows from operating leases $ 2,980 $ 4,336 Operating cash flows from finance leases $ 11 $ 15 Financing cash flows from finance leases $ 96 $ 105 Right-of-use assets obtained in exchange for lease obligations (noncash): Operating leases $ 3,496 $ 5,633 Finance leases $ — $ — Supplemental balance sheet information related to leases is as follows: June 30, December 31, Operating Leases Operating lease right-of-use assets $ 16,609 $ 16,515 Current portion of long-term lease obligations $ 7,942 $ 7,588 Long-term lease obligations 8,783 8,958 Total operating lease liabilities $ 16,725 $ 16,546 Finance Leases Property and equipment, at cost $ 1,479 $ 1,479 Accumulated depreciation (806) (702) Property and equipment, net $ 673 $ 777 Current maturities of long-term debt $ 168 $ 188 Long-term debt 295 372 Total finance lease liabilities $ 463 $ 560 Weighted Average Remaining Lease Term Operating leases 3.4 3.2 Finance leases 2.9 3.2 Weighted Average Discount Rate Operating leases 5.5 % 5.7 % Finance leases 4.2 % 4.2 % Maturities of lease liabilities are as follows: Operating Finance Year Ending December 31, 2021 (excluding the six months ended June 30, 2021) $ 3,715 $ 101 2022 6,510 161 2023 3,866 154 2024 1,820 77 2025 1,002 — 2026 928 — Thereafter 628 — Total lease payments $ 18,469 $ 493 Less imputed interest (1,744) (30) Total $ 16,725 $ 463

Commitments and Contingencies

Commitments and Contingencies	6 Months Ended
	Jun. 30, 2021
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	11. COMMITMENTS AND CONTINGENCIES The Company is required by its insurance providers to obtain and hold standby letters of credit. These letters of credit serve as a guarantee by the banking institution to pay the Company’s insurance providers the incurred claim costs attributable to its general liability, workers compensation and automobile liability claims, up to the amount stated in the standby letters of credit, in the event that these claims were not paid by the Company. These letters of credit are cash collateralized, resulting in the cash being designated as restricted. The Company, including its construction joint ventures and its consolidated 50% owned subsidiaries, is now and may in the future be involved as a party to various legal proceedings that are incidental to the ordinary course of business. Management, after consultation with legal counsel, does not believe that the outcome of these actions will have a material impact on the Condensed Consolidated Financial Statements of the Company.

Income Taxes

Income Taxes	6 Months Ended
	Jun. 30, 2021
Income Tax Disclosure [Abstract]
Income Taxes	12. INCOME TAXES The Company and its subsidiaries are based in the U.S. and file federal and various state income tax returns. The components of the provision for income taxes were as follows: Three Months Ended June 30, Six Months Ended June 30, 2021 2020 2021 2020 Current tax expense $ 1,027 $ 1,938 $ 1,645 $ 2,209 Deferred tax expense 7,152 5,310 11,294 6,223 Income tax expense $ 8,179 $ 7,248 $ 12,939 $ 8,432 Cash paid for income taxes $ 1,700 $ — $ 1,700 $ 44 The 2021 effective income tax rate varied from the statutory rate primarily as a result of state income taxes, nondeductible compensation and other permanent differences. Due to net operating loss carryforwards, the Company expects no cash payments for federal income taxes for 2021 or 2020. The Company makes cash payments for state income taxes in states in which the Company does not have net operating loss carry forwards. At December 31, 2020 the Company had federal and state net operating loss (“NOL”) carryforwards of $58,719 and $36,381, respectively, which expire at various dates in the next 18 years for U.S. federal income tax and in the next 7 to 18 years for the various state jurisdictions where we operate. Such NOL carryforwards expire beginning in 2028 through 2039. As a result of the Company’s analysis, management has determined that the Company does not have any material uncertain tax positions.

Stock Incentive Plan and Other

Stock Incentive Plan and Other Equity Activity	6 Months Ended
	Jun. 30, 2021
Stockholders' Equity Note [Abstract]
Stock Incentive Plan And Other Equity Activity	13. STOCK INCENTIVE PLAN AND OTHER EQUITY ACTIVITY General —The Company has a stock incentive plan (the “Stock Incentive Plan”) and an employee stock purchase plan (the “ESPP”) that are administered by the Compensation and Talent Development Committee of the Board of Directors. Under the Stock Incentive Plan, the Company can issue shares to employees and directors in the form of restricted stock awards (“RSAs”), restricted stock units (“RSUs”) and performance share units (“PSUs”). Changes in common stock, additional paid in capital and treasury stock during the six months ended June 30, 2021 primarily relate to activity associated with the Stock Incentive Plan, the ESPP and shares withheld for taxes. Share Grants —During the six months ended June 30, 2021, the Company granted the following awards under the Stock Incentive Plan: Shares Weighted Average Grant-Date Fair Value per Share RSAs 26 $ 23.22 RSUs 108 $ 20.55 PSUs (at target) 139 $ 20.54 Total shares granted 273 Share Issuances —During the six months ended June 30, 2021, the Company issued the following shares under the Stock Incentive Plan and the ESPP: Shares RSAs (issued upon grant) 26 RSUs (issued upon vesting) 40 PSUs (issued upon vesting) 621 ESPP (issued upon sale) 13 Total shares issued 700 Stock-Based Compensation Expense —During the three and six months ended June 30, 2021, the Company recognized $2,015 and $3,850, respectively, of stock-based compensation expense, and during the three and six months ended June 30, 2020, the Company recognized $3,962 and $6,196 of stock-based compensation expense, respectively, primarily within general and administrative expenses. The Company recognizes forfeitures as they occur, rather than estimating expected forfeitures. Included within total stock-based compensation expense for the three and six months ended June 30, 2021 is $22 and $47, respectively, of expense related to the ESPP, and during the three and six months ended June 30, 2020, the Company recognized $18 and $36, respectively, of expense related to the ESPP. Shares Withheld for Taxes —The Company withheld zero and 246 shares for taxes on RSU/PSU stock-based compensation vestings for $0 and $5,619 during the three and six months ended June 30, 2021, respectively. AOCI —During the three and six months ended June 30, 2021, changes in AOCI were a result of net gains (losses) recognized in OCI and amounts reclassified from AOCI into earnings related to our interest rate derivative. See Note 9 - Financial Instruments for further discussion.

Earnings Per Share

Earnings Per Share	6 Months Ended
	Jun. 30, 2021
Earnings Per Share [Abstract]
Earnings Per Share	14. EARNINGS PER SHARE The following table reconciles the numerators and denominators of the basic and diluted earnings per share computations for the three and six months ended June 30, 2021 and 2020: Three Months Ended June 30, Six Months Ended June 30, 2021 2020 2021 2020 Numerator: Net income attributable to Sterling common stockholders $ 20,056 $ 18,210 $ 30,611 $ 21,325 Denominator: Weighted average common shares outstanding — basic 28,582 27,941 28,433 27,794 Shares for dilutive unvested stock and warrants 472 16 445 93 Weighted average common shares outstanding — diluted 29,054 27,957 28,878 27,887 Basic net income per share attributable to Sterling common stockholders $ 0.70 $ 0.65 $ 1.08 $ 0.77 Diluted net income per share attributable to Sterling common stockholders $ 0.69 $ 0.65 $ 1.06 $ 0.76

Supplemental Cash Flow Informat

Supplemental Cash Flow Information	6 Months Ended
	Jun. 30, 2021
Supplemental Cash Flow Elements [Abstract]
Supplemental Cash Flow Information	15. SUPPLEMENTAL CASH FLOW INFORMATION Operating Assets and Liabilities— The following table summarizes the changes in the components of operating assets and liabilities: Six Months Ended June 30, 2021 2020 Accounts receivable $ (34,105) $ (27,713) Contracts in progress, net 26,008 22,964 Receivables from and equity in construction joint ventures (1,358) (3,200) Other current and non-current assets (8,448) (306) Accounts payable 38,308 (6,495) Accrued compensation and other liabilities 3,936 10,453 Members' interest subject to mandatory redemption and undistributed earnings 3,703 4,748 Changes in operating assets and liabilities $ 28,044 $ 451

Segment Information

Segment Information	6 Months Ended
	Jun. 30, 2021
Segment Reporting [Abstract]
Segment Information	16. SEGMENT INFORMATION The Company’s internal and public segment reporting are aligned based upon the services offered by its operating segments. The Company’s operations consist of three reportable segments: Heavy Civil, Specialty Services and Residential. The Company’s Chief Operating Decision Maker evaluates the performance of the operating segment based upon revenue and income from operations. Each segment’s income from operations reflects corporate costs, allocated based primarily upon revenue. The following table presents total revenue and income from operations by reportable segment for the three and six months ended June 30, 2021 and 2020: Three Months Ended June 30, Six Months Ended June 30, 2021 2020 2021 2020 Revenues Heavy Civil $ 203,153 $ 220,448 $ 350,207 $ 376,063 Specialty Services 151,904 135,703 275,992 240,426 Residential 46,609 43,887 90,783 80,237 Total Revenues $ 401,666 $ 400,038 $ 716,982 $ 696,726 Operating Income Heavy Civil $ 4,404 $ 3,896 $ 5,494 $ 274 Specialty Services 22,907 23,246 39,084 34,360 Residential 5,409 6,043 10,897 11,127 Subtotal 32,720 33,185 55,475 45,761 Acquisition related costs — (139) — (612) Total Operating Income $ 32,720 $ 33,046 $ 55,475 $ 45,149

Basis of Presentation and Sig_2

Basis of Presentation and Significant Accounting Policies (Policies)	6 Months Ended
	Jun. 30, 2021
Accounting Policies [Abstract]
Presentation Basis	Presentation Basis— The accompanying Condensed Consolidated Financial Statements are presented in accordance with accounting policies generally accepted in the United States (“GAAP”) and reflect all wholly owned subsidiaries and those entities the Company is required to consolidate. See Note 4 - Consolidated 50% Owned Subsidiaries and Note 5 - Construction Joint Ventures for further discussion of the Company’s consolidation policy for those entities that are not wholly owned. In the opinion of management, all adjustments, consisting only of normal recurring adjustments, considered necessary for a fair presentation have been included. All significant intercompany accounts and transactions have been eliminated in consolidation. Values presented within tables (excluding per share data) are in thousands. Reclassifications have been made to historical financial data in the Condensed Consolidated Financial Statements to conform to the current year presentation.
Estimates and Judgments	Estimates and Judgments— The preparation of the accompanying Condensed Consolidated Financial Statements in conformance with GAAP requires management to make estimates and judgments 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 accounting estimates of the Company require a higher degree of judgment than others in their application. These include the recognition of revenue and earnings from construction contracts over time, the valuation of long-lived assets, goodwill and purchase accounting estimates. Management continually evaluates all of its estimates and judgments based on available information and experience; however, actual results could differ from these estimates.
Accounts Receivable	Accounts Receivable— Receivables are generally based on amounts billed to the customer in accordance with contractual provisions. Receivables are written off based on the individual credit evaluation and specific circumstances of the customer, when such treatment is warranted. The Company performs a review of outstanding receivables, historical collection information and existing economic conditions to determine if there are potential uncollectible receivables. At June 30, 2021 and December 31, 2020, our allowance for our estimate of expected credit losses was zero. As is customary, we have agreed to indemnify our bonding company for all losses incurred by it in connection with bonds that are issued, and we have granted our bonding company a security interest in certain assets, including accounts receivable, as collateral for such obligations.
Contracts in Progress	Contracts in Progress— For performance obligations satisfied over time, amounts are billed as work progresses in accordance with agreed-upon contractual terms, either at periodic intervals (e.g., biweekly or monthly) or upon achievement of contractual milestones. Typically, Sterling bills for advances or deposits from its customers before revenue is recognized, resulting in contract liabilities. However, the Company occasionally bills subsequent to revenue recognition, resulting in contract assets. Many of the contracts under which the Company performs work also contain retainage provisions. Retainage refers to that portion of our billings held for payment by the customer pending satisfactory completion of the project. Unless reserved, the Company assumes that all amounts retained by customers under such provisions are fully collectible. At June 30, 2021 and December 31, 2020, contract assets included $45,924 and $44,412 of retainage, respectively, and contract liabilities included $39,682 and $33,856 of retainage, respectively. Retainage on active contracts is classified as current regardless of the term of the contract and is generally collected within one year of the completion of a contract. We anticipate collecting approximately 68% of our June 30, 2021 retainage during the next twelve months. These assets and liabilities are reported on the Condensed Consolidated Balance Sheet within “Contract assets” and “Contract liabilities” on a contract-by-contract basis at the end of each reporting period. Revenue recognized for the three and six months ended June 30, 2021 that was included in the contract liability balance on December 31, 2020 was $141,813 and $297,370, respectively. Revenue recognized for the three and six months ended June 30, 2020 that was included in the contract liability balance on December 31, 2019 was $132,225 and $278,491, respectively.
Cash and Restricted Cash	Cash and Restricted Cash— Our cash is comprised of highly liquid investments with maturities of three months or less. Restricted cash of $6,411 and $6,457 is included in “Other current assets” on the Condensed Consolidated Balance Sheets at June 30, 2021 and December 31, 2020, respectively. This primarily represents cash deposited by the Company into separate accounts and designated as collateral for standby letters of credit in the same amount in accordance with contractual agreements.

Revenue From Customers (Tables)

Revenue From Customers (Tables)	6 Months Ended
	Jun. 30, 2021
Revenue from Contract with Customer [Abstract]
Schedule of Backlog By Segment	The following table presents the Company’s backlog, by segment: June 30, December 31, Heavy Civil Backlog $ 1,183,122 $ 898,183 Specialty Services Backlog 387,519 277,205 Total Heavy Civil and Specialty Services Backlog $ 1,570,641 $ 1,175,388
Disaggregation of Revenue	The following tables present the Company’s revenue disaggregated by major end market and contract type: Three Months Ended June 30, Six Months Ended June 30, Revenues by major end market 2021 2020 2021 2020 Heavy Highway $ 139,189 $ 152,526 $ 238,705 $ 248,900 Aviation 36,754 34,867 63,976 63,324 Water Containment and Treatment 16,208 16,529 30,427 38,338 Other 11,002 16,526 17,099 25,501 Heavy Civil Revenues 203,153 220,448 350,207 376,063 Land Development 123,743 105,639 220,315 181,884 Commercial 28,161 30,064 55,677 58,542 Specialty Services Revenues 151,904 135,703 275,992 240,426 Residential Revenues 46,609 43,887 90,783 80,237 Total Revenues $ 401,666 $ 400,038 $ 716,982 $ 696,726 Revenues by contract type Fixed-Unit Price $ 225,886 $ 203,692 $ 403,434 $ 345,431 Lump Sum 127,416 147,460 218,571 261,712 Residential and Other 48,364 48,886 94,977 89,583 Total Revenues $ 401,666 $ 400,038 $ 716,982 $ 696,726

Consolidated 50% Owned Subsid_2

Consolidated 50% Owned Subsidiaries (Tables)	6 Months Ended
	Jun. 30, 2021
Noncontrolling Interest [Abstract]
Summary of Liability Breakdown	The liability consists of the following: June 30, December 31, Members’ interest subject to mandatory redemption $ 40,000 $ 40,000 Net accumulated earnings 16,488 11,290 Total liability $ 56,488 $ 51,290
Summary of Financial Information	Summary financial information for Myers is as follows: Three Months Ended June 30, Six Months Ended June 30, 2021 2020 2021 2020 Revenues $ 43,137 $ 54,364 $ 71,094 $ 98,726 Operating income $ 747 $ 1,049 $ 1,465 $ 1,204 Net income $ 366 $ 526 $ 717 $ 605 Three Months Ended June 30, Six Months Ended June 30, 2021 2020 2021 2020 Revenues $ 9,325 $ 3,404 $ 17,566 $ 7,468 Operating income $ 613 $ 375 $ 3,140 $ 671 Net income $ 615 $ 376 $ 3,143 $ 675 Three Months Ended June 30, Six Months Ended June 30, 2021 2020 2021 2020 Revenues $ 62,489 $ 43,466 $ 111,906 $ 70,312 Income before tax $ 8,780 $ 4,516 $ 13,415 $ 6,673 Sterling’s noncontrolling interest: Revenues $ 26,994 $ 19,377 $ 48,938 $ 32,459 Income before tax $ 3,676 $ 1,968 $ 5,811 $ 3,017

Construction Joint Ventures (Ta

Construction Joint Ventures (Tables)	6 Months Ended
	Jun. 30, 2021
Equity Method Investments and Joint Ventures [Abstract]
Condensed Income Statement	Summary financial information for Myers is as follows: Three Months Ended June 30, Six Months Ended June 30, 2021 2020 2021 2020 Revenues $ 43,137 $ 54,364 $ 71,094 $ 98,726 Operating income $ 747 $ 1,049 $ 1,465 $ 1,204 Net income $ 366 $ 526 $ 717 $ 605 Three Months Ended June 30, Six Months Ended June 30, 2021 2020 2021 2020 Revenues $ 9,325 $ 3,404 $ 17,566 $ 7,468 Operating income $ 613 $ 375 $ 3,140 $ 671 Net income $ 615 $ 376 $ 3,143 $ 675 Three Months Ended June 30, Six Months Ended June 30, 2021 2020 2021 2020 Revenues $ 62,489 $ 43,466 $ 111,906 $ 70,312 Income before tax $ 8,780 $ 4,516 $ 13,415 $ 6,673 Sterling’s noncontrolling interest: Revenues $ 26,994 $ 19,377 $ 48,938 $ 32,459 Income before tax $ 3,676 $ 1,968 $ 5,811 $ 3,017
Condensed Balance Sheet	June 30, December 31, Current assets $ 138,804 $ 143,608 Current liabilities $ (95,350) $ (141,295) Sterling’s receivables from and equity in construction joint ventures $ 18,011 $ 16,653

Property and Equipment (Tables)

Property and Equipment (Tables)	6 Months Ended
	Jun. 30, 2021
Property, Plant and Equipment [Abstract]
Summary of Property and Equipment	Property and equipment are summarized as follows: June 30, December 31, Construction and transportation equipment $ 252,797 $ 231,799 Buildings and improvements 22,493 21,025 Land 3,891 3,891 Office equipment 3,046 3,012 Total property and equipment 282,227 259,727 Less accumulated depreciation (140,212) (133,059) Total property and equipment, net $ 142,015 $ 126,668

Other Intangible Assets (Tables

Other Intangible Assets (Tables)	6 Months Ended
	Jun. 30, 2021
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Finite-Lived Intangible Assets	The following table presents our acquired finite-lived intangible assets, including the weighted-average useful lives for each major intangible asset category and in total: June 30, 2021 December 31, 2020 Weighted Gross Accumulated Gross Accumulated Customer relationships 25 $ 232,623 $ (21,099) $ 232,623 $ (16,360) Trade name 23 30,107 (3,967) 30,107 (3,209) Non-compete agreements 5 2,487 (996) 2,487 (761) Total 24 $ 265,217 $ (26,062) $ 265,217 $ (20,330)

Debt (Tables)

Debt (Tables)	6 Months Ended
	Jun. 30, 2021
Debt Disclosure [Abstract]
Schedule of Long-term Debt Instruments	The Company’s outstanding debt was as follows: June 30, December 31, Term Loan Facility $ 315,000 $ 355,000 Revolving Credit Facility — — Credit Facility 315,000 355,000 Other debt 17,335 20,397 Total debt 332,335 375,397 Less - Current maturities of long-term debt (23,186) (77,434) Less - Unamortized debt issuance costs (5,618) (6,714) Total long-term debt $ 303,531 $ 291,249

Financial Instruments (Tables)

Financial Instruments (Tables)	6 Months Ended
	Jun. 30, 2021
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule of Derivative Liabilities at Fair Value	The following table presents the fair value of the interest rate derivative by valuation hierarchy and balance sheet classification: June 30, 2021 December 31, 2020 Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Total Other current liabilities $ — $ (3,794) $ — $ (3,794) $ — $ (4,427) $ — $ (4,427) Other non-current liabilities — (1,108) — (1,108) — (2,629) — (2,629) Total liabilities at fair value $ — $ (4,902) $ — $ (4,902) $ — $ (7,056) $ — $ (7,056)
Schedule of Changes in AOCI	The following table presents the total value recognized in OCI and reclassified from AOCI into earnings during the three and six months ended June 30, 2021 and 2020 for derivatives designated as cash flow hedges: Three Months Ended June 30, 2021 Six Months Ended June 30, 2021 Before Tax Tax Net of Tax Before Tax Tax Net of Tax Net gain (loss) recognized in OCI $ (82) $ 19 $ (63) $ 44 $ (10) $ 34 Net amount reclassified from AOCI into earnings (1) 1,024 (233) 791 2,058 (469) 1,589 Change in other comprehensive income $ 942 $ (214) $ 728 $ 2,102 $ (479) $ 1,623 Three Months Ended June 30, 2020 Six Months Ended June 30, 2020 Before Tax Tax Net of Tax Before Tax Tax Net of Tax Net gain (loss) recognized in OCI $ (1,031) $ 232 $ (799) $ (10,205) $ 2,296 $ (7,909) Net amount reclassified from AOCI into earnings 963 (217) 746 1,026 (231) 795 Change in other comprehensive income $ (68) $ 15 $ (53) $ (9,179) $ 2,065 $ (7,114) (1) Net unrealized losses totaling $3,611 are anticipated to be reclassified from AOCI into earnings during the next 12 months due to settlement of the associated underlying obligations.

Lease Obligations (Tables)

Lease Obligations (Tables)	6 Months Ended
	Jun. 30, 2021
Leases [Abstract]
Schedule of Lease Expenses	The components of lease expense are as follows: Three Months Ended June 30, Six Months Ended June 30, 2021 2020 2021 2020 Operating lease cost $ 1,510 $ 2,075 $ 3,022 $ 4,234 Short-term lease cost $ 2,911 $ 3,745 $ 5,035 $ 7,026 Finance lease cost: Amortization of right-of-use assets $ 46 $ 49 $ 96 $ 105 Interest on lease liabilities 5 7 11 15 Total finance lease cost $ 51 $ 56 $ 107 $ 120 Supplemental cash flow information related to leases is as follows: Six Months Ended June 30, 2021 2020 Cash paid for amounts included in the measurement of lease liabilities: Operating cash flows from operating leases $ 2,980 $ 4,336 Operating cash flows from finance leases $ 11 $ 15 Financing cash flows from finance leases $ 96 $ 105 Right-of-use assets obtained in exchange for lease obligations (noncash): Operating leases $ 3,496 $ 5,633 Finance leases $ — $ — Supplemental balance sheet information related to leases is as follows: June 30, December 31, Operating Leases Operating lease right-of-use assets $ 16,609 $ 16,515 Current portion of long-term lease obligations $ 7,942 $ 7,588 Long-term lease obligations 8,783 8,958 Total operating lease liabilities $ 16,725 $ 16,546 Finance Leases Property and equipment, at cost $ 1,479 $ 1,479 Accumulated depreciation (806) (702) Property and equipment, net $ 673 $ 777 Current maturities of long-term debt $ 168 $ 188 Long-term debt 295 372 Total finance lease liabilities $ 463 $ 560 Weighted Average Remaining Lease Term Operating leases 3.4 3.2 Finance leases 2.9 3.2 Weighted Average Discount Rate Operating leases 5.5 % 5.7 % Finance leases 4.2 % 4.2 %
Maturities of Lease Liabilities, Operating Leases	Maturities of lease liabilities are as follows: Operating Finance Year Ending December 31, 2021 (excluding the six months ended June 30, 2021) $ 3,715 $ 101 2022 6,510 161 2023 3,866 154 2024 1,820 77 2025 1,002 — 2026 928 — Thereafter 628 — Total lease payments $ 18,469 $ 493 Less imputed interest (1,744) (30) Total $ 16,725 $ 463
Maturities of Lease Liabilities, Finance Leases	Maturities of lease liabilities are as follows: Operating Finance Year Ending December 31, 2021 (excluding the six months ended June 30, 2021) $ 3,715 $ 101 2022 6,510 161 2023 3,866 154 2024 1,820 77 2025 1,002 — 2026 928 — Thereafter 628 — Total lease payments $ 18,469 $ 493 Less imputed interest (1,744) (30) Total $ 16,725 $ 463

Income Taxes (Tables)

Income Taxes (Tables)	6 Months Ended
	Jun. 30, 2021
Income Tax Disclosure [Abstract]
Schedule of Components of Income Taxes	The components of the provision for income taxes were as follows: Three Months Ended June 30, Six Months Ended June 30, 2021 2020 2021 2020 Current tax expense $ 1,027 $ 1,938 $ 1,645 $ 2,209 Deferred tax expense 7,152 5,310 11,294 6,223 Income tax expense $ 8,179 $ 7,248 $ 12,939 $ 8,432 Cash paid for income taxes $ 1,700 $ — $ 1,700 $ 44

Stock Incentive Plan and Othe_2

Stock Incentive Plan and Other Equity Activity (Tables)	6 Months Ended
	Jun. 30, 2021
Stockholders' Equity Note [Abstract]
Schedule of Share Grants and Issuances	During the six months ended June 30, 2021, the Company granted the following awards under the Stock Incentive Plan: Shares Weighted Average Grant-Date Fair Value per Share RSAs 26 $ 23.22 RSUs 108 $ 20.55 PSUs (at target) 139 $ 20.54 Total shares granted 273 Shares RSAs (issued upon grant) 26 RSUs (issued upon vesting) 40 PSUs (issued upon vesting) 621 ESPP (issued upon sale) 13 Total shares issued 700

Earnings Per Share (Tables)

Earnings Per Share (Tables)	6 Months Ended
	Jun. 30, 2021
Earnings Per Share [Abstract]
Schedule of Earnings Per Share, Basic and Diluted	The following table reconciles the numerators and denominators of the basic and diluted earnings per share computations for the three and six months ended June 30, 2021 and 2020: Three Months Ended June 30, Six Months Ended June 30, 2021 2020 2021 2020 Numerator: Net income attributable to Sterling common stockholders $ 20,056 $ 18,210 $ 30,611 $ 21,325 Denominator: Weighted average common shares outstanding — basic 28,582 27,941 28,433 27,794 Shares for dilutive unvested stock and warrants 472 16 445 93 Weighted average common shares outstanding — diluted 29,054 27,957 28,878 27,887 Basic net income per share attributable to Sterling common stockholders $ 0.70 $ 0.65 $ 1.08 $ 0.77 Diluted net income per share attributable to Sterling common stockholders $ 0.69 $ 0.65 $ 1.06 $ 0.76

Supplemental Cash Flow Inform_2

Supplemental Cash Flow Information (Tables)	6 Months Ended
	Jun. 30, 2021
Supplemental Cash Flow Elements [Abstract]
Schedule of Cash Flow, Supplemental Disclosures	The following table summarizes the changes in the components of operating assets and liabilities: Six Months Ended June 30, 2021 2020 Accounts receivable $ (34,105) $ (27,713) Contracts in progress, net 26,008 22,964 Receivables from and equity in construction joint ventures (1,358) (3,200) Other current and non-current assets (8,448) (306) Accounts payable 38,308 (6,495) Accrued compensation and other liabilities 3,936 10,453 Members' interest subject to mandatory redemption and undistributed earnings 3,703 4,748 Changes in operating assets and liabilities $ 28,044 $ 451

Segment Information (Tables)

Segment Information (Tables)	6 Months Ended
	Jun. 30, 2021
Segment Reporting [Abstract]
Schedule of Segment Reporting Information, by Segment	The following table presents total revenue and income from operations by reportable segment for the three and six months ended June 30, 2021 and 2020: Three Months Ended June 30, Six Months Ended June 30, 2021 2020 2021 2020 Revenues Heavy Civil $ 203,153 $ 220,448 $ 350,207 $ 376,063 Specialty Services 151,904 135,703 275,992 240,426 Residential 46,609 43,887 90,783 80,237 Total Revenues $ 401,666 $ 400,038 $ 716,982 $ 696,726 Operating Income Heavy Civil $ 4,404 $ 3,896 $ 5,494 $ 274 Specialty Services 22,907 23,246 39,084 34,360 Residential 5,409 6,043 10,897 11,127 Subtotal 32,720 33,185 55,475 45,761 Acquisition related costs — (139) — (612) Total Operating Income $ 32,720 $ 33,046 $ 55,475 $ 45,149

Nature of Operations (Details)

Nature of Operations (Details)	6 Months Ended
	Jun. 30, 2021segment
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of reportable segments	3

Basis of Presentation and Sig_3

Basis of Presentation and Significant Accounting Policies (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Property, Plant and Equipment [Line Items]
Allowance for doubtful accounts against contracts receivable	$ 0		$ 0		$ 0
Contract receivables	45,924,000		45,924,000		44,412,000
Contract liabilities, retainage	$ 39,682,000		$ 39,682,000		33,856,000
Percentage of receivables estimated to be collected in next fiscal year	68.00%		68.00%
Contract liability recognized during period	$ 141,813,000		$ 297,370,000
Contract liability revenue recognized		$ 132,225,000		$ 278,491,000
Restricted cash	6,411,000	$ 4,895,000	6,411,000	$ 4,895,000
Other current assets
Property, Plant and Equipment [Line Items]
Restricted cash	$ 6,411,000		$ 6,411,000		$ 6,457,000

Revenue From Customers - Backlo

Revenue From Customers - Backlog By Segment (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Disaggregation of Revenue [Line Items]
Backlog	$ 1,570,641	$ 1,175,388
Heavy Civil
Disaggregation of Revenue [Line Items]
Backlog	1,183,122	898,183
Specialty Services
Disaggregation of Revenue [Line Items]
Backlog	$ 387,519	$ 277,205

Revenue From Customers - Additi

Revenue From Customers - Additional Information (Details) - Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-07-01	Jun. 30, 2021
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation expected to be recognized over next twelve months	59.00%
Remaining performance obligation period	12 months

Revenue From Customers - Disagg

Revenue From Customers - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Disaggregation of Revenue [Line Items]
Revenues	$ 401,666	$ 400,038	$ 716,982	$ 696,726
Fixed-Unit Price
Disaggregation of Revenue [Line Items]
Revenues	225,886	203,692	403,434	345,431
Lump Sum
Disaggregation of Revenue [Line Items]
Revenues	127,416	147,460	218,571	261,712
Residential and Other
Disaggregation of Revenue [Line Items]
Revenues	48,364	48,886	94,977	89,583
Heavy Civil
Disaggregation of Revenue [Line Items]
Revenues	203,153	220,448	350,207	376,063
Heavy Civil | Heavy Highway
Disaggregation of Revenue [Line Items]
Revenues	139,189	152,526	238,705	248,900
Heavy Civil | Aviation
Disaggregation of Revenue [Line Items]
Revenues	36,754	34,867	63,976	63,324
Heavy Civil | Water Containment and Treatment
Disaggregation of Revenue [Line Items]
Revenues	16,208	16,529	30,427	38,338
Heavy Civil | Other
Disaggregation of Revenue [Line Items]
Revenues	11,002	16,526	17,099	25,501
Specialty Services
Disaggregation of Revenue [Line Items]
Revenues	151,904	135,703	275,992	240,426
Specialty Services | Land Development
Disaggregation of Revenue [Line Items]
Revenues	123,743	105,639	220,315	181,884
Specialty Services | Commercial
Disaggregation of Revenue [Line Items]
Revenues	28,161	30,064	55,677	58,542
Residential
Disaggregation of Revenue [Line Items]
Revenues	$ 46,609	$ 43,887	$ 90,783	$ 80,237

Revenue From Customers - Narrat

Revenue From Customers - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Costs and Estimated Earnings in Excess of Billings
Disaggregation of Revenue [Line Items]
Contracts receivable unpaid project contract price	$ 14,300		$ 14,300		$ 7,142
Operating income (Loss)
Disaggregation of Revenue [Line Items]
Estimated construction gain (loss) before tax	$ 3,727	$ 2,197	$ 12,032	$ 2,292

Consolidated 50% Owned Subsid_3

Consolidated 50% Owned Subsidiaries - Narrative (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021USD ($)entity	Jun. 30, 2020USD ($)entity	Jun. 30, 2021USD ($)insurancePolicyentity	Jun. 30, 2020USD ($)entity	Dec. 31, 2020USD ($)
Noncontrolling Interest [Line Items]
Ownership interest in subsidiaries	50.00%	50.00%	50.00%	50.00%
Number of entities | entity	2	2	2	2
Members’ interest subject to mandatory redemption	$ 40,000		$ 40,000		$ 40,000
Number of death and disability insurance policies | insurancePolicy			2
Total disability insurance policies, per policy amount	20,000		$ 20,000
Myers
Noncontrolling Interest [Line Items]
Net accumulated earnings	4,800	$ 4,600	6,600	$ 6,300
Variable Interest Entity, Primary Beneficiary | Myers
Noncontrolling Interest [Line Items]
Members’ interest subject to mandatory redemption	$ 20,000		$ 20,000

Consolidated 50% Owned Subsid_4

Consolidated 50% Owned Subsidiaries - Components of Noncontrolling Interest (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Noncontrolling Interest [Abstract]
Members’ interest subject to mandatory redemption	$ 40,000	$ 40,000
Net accumulated earnings	16,488	11,290
Total liability	$ 56,488	$ 51,290

Consolidated 50% Owned Subsid_5

Consolidated 50% Owned Subsidiaries Consolidated 50% Owned Subsidiaries - Statement of Operations (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Variable Interest Entity [Line Items]
Operating income	$ 32,720	$ 33,046	$ 55,475	$ 45,149
Net income	20,056	18,210	30,611	21,325
Variable Interest Entity, Primary Beneficiary | Myers
Variable Interest Entity [Line Items]
Revenues	43,137	54,364	71,094	98,726
Operating income	747	1,049	1,465	1,204
Net income	$ 366	$ 526	$ 717	$ 605

Construction Joint Ventures - S

Construction Joint Ventures - SEMA Financials (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Schedule of Equity Method Investments [Line Items]
Operating income	$ 32,720	$ 33,046	$ 55,475	$ 45,149
Net income	20,056	18,210	$ 30,611	21,325
RLW | Joint Ventures
Schedule of Equity Method Investments [Line Items]
Ownership percentage			51.00%
SEMA Construction Inc | Joint Ventures | Variable Interest Entity, Primary Beneficiary
Schedule of Equity Method Investments [Line Items]
Revenues	9,325	3,404	$ 17,566	7,468
Operating income	613	375	3,140	671
Net income	$ 615	$ 376	$ 3,143	$ 675

Construction Joint Ventures - C

Construction Joint Ventures - Construction Joint Ventures, Partner Share (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Schedule of Equity Method Investments [Line Items]
Current assets	$ 434,092	$ 361,543
Current liabilities	(346,242)	(321,884)
Receivables from and equity in construction joint ventures	18,011	16,653
Joint Ventures | Equity Method Investment, Nonconsolidated Investee or Group of Investees
Schedule of Equity Method Investments [Line Items]
Current assets	138,804	143,608
Current liabilities	(95,350)	(141,295)
Receivables from and equity in construction joint ventures	$ 18,011	$ 16,653

Construction Joint Ventures - I

Construction Joint Ventures - Income Statement Information (Details) - Joint Ventures - Equity Method Investment, Nonconsolidated Investee or Group of Investees - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Schedule of Equity Method Investments [Line Items]
Revenues	$ 62,489	$ 43,466	$ 111,906	$ 70,312
Income before tax	8,780	4,516	13,415	6,673
Sterling’s noncontrolling interest:
Revenues	26,994	19,377	48,938	32,459
Income before tax	$ 3,676	$ 1,968	$ 5,811	$ 3,017

Property and Equipment (Details

Property and Equipment (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 282,227		$ 282,227		$ 259,727
Less accumulated depreciation	(140,212)		(140,212)		(133,059)
Total property and equipment, net	142,015		142,015		126,668
Depreciation	5,536	$ 5,390	10,975	$ 10,838
Construction and transportation equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	252,797		252,797		231,799
Buildings and improvements
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	22,493		22,493		21,025
Land
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	3,891		3,891		3,891
Office equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 3,046		$ 3,046		$ 3,012

Other Intangible Assets (Detail

Other Intangible Assets (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Finite-Lived Intangible Assets [Line Items]
Weighted Average Life (Years)			24 years
Gross Carrying Amount	$ 265,217		$ 265,217		$ 265,217
Accumulated Amortization	(26,062)		(26,062)		(20,330)
Amortization of intangible assets	2,866	$ 2,866	$ 5,732	$ 5,703
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Weighted Average Life (Years)			25 years
Gross Carrying Amount	232,623		$ 232,623		232,623
Accumulated Amortization	(21,099)		$ (21,099)		(16,360)
Trade name
Finite-Lived Intangible Assets [Line Items]
Weighted Average Life (Years)			23 years
Gross Carrying Amount	30,107		$ 30,107		30,107
Accumulated Amortization	(3,967)		$ (3,967)		(3,209)
Non-compete agreements
Finite-Lived Intangible Assets [Line Items]
Weighted Average Life (Years)			5 years
Gross Carrying Amount	2,487		$ 2,487		2,487
Accumulated Amortization	$ (996)		$ (996)		$ (761)

Debt - Long-term Debt (Details)

Debt - Long-term Debt (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Debt Instrument [Line Items]
Long-term debt	$ 332,335	$ 375,397
Less - Current maturities of long-term debt	(23,186)	(77,434)
Less - Unamortized debt issuance costs	(5,618)	(6,714)
Long term debt	303,531	291,249
Other Debt
Debt Instrument [Line Items]
Long-term debt	17,335	20,397
Secured Debt | Term Loan Facility
Debt Instrument [Line Items]
Long-term debt	315,000	355,000
Secured Debt | Revolving Credit Facility
Debt Instrument [Line Items]
Long-term debt	0	0
Secured Debt | Credit Facility
Debt Instrument [Line Items]
Long-term debt	$ 315,000	$ 355,000

Debt - Narrative (Details)

Debt - Narrative (Details)	Jun. 30, 2021USD ($)loanentity	Jun. 30, 2021USD ($)loanentity	Mar. 31, 2021USD ($)	Jun. 30, 2020USD ($)loanentity	Jun. 30, 2021USD ($)loanentity	Jun. 30, 2020USD ($)entity	Dec. 31, 2024USD ($)	Dec. 31, 2023USD ($)	Dec. 31, 2022USD ($)	Dec. 31, 2021USD ($)	Dec. 31, 2020USD ($)	Oct. 02, 2019USD ($)
Debt Instrument [Line Items]
Long-term debt	$ 332,335,000	$ 332,335,000			$ 332,335,000						$ 375,397,000
Amortization of debt issuance costs		604,000		$ 740,000	1,264,000	$ 1,492,000
Gain (loss) on extinguishment of debt		$ 1,401,000		$ 0	$ 1,064,000	$ 0
Number of entities | entity	2	2		2	2	2
Ownership interest in subsidiaries	50.00%	50.00%		50.00%	50.00%	50.00%
Paycheck protection loans received, CARES Act | loan				3
Paycheck protection program loan amount, CARES Act				$ 9,800,000		$ 9,800,000
Loans the SBA forgave, CARES Act | loan	1	1			1
Loans remaining, CARES Act | loan	2	2			2
Credit Agreement
Debt Instrument [Line Items]
Cash flow prepayment term					5 days
Term Loan Facility
Debt Instrument [Line Items]
Gain (loss) on extinguishment of debt				$ (94,000)		$ (431,000)
Paycheck Protection Program
Debt Instrument [Line Items]
Gain (loss) on extinguishment of debt		$ 1,495,000
Loan amount forgiven		$ 3,000,000
Secured Debt | Credit Agreement
Debt Instrument [Line Items]
Debt instrument face amount												$ 475,000,000
Secured Debt | Term Loan Facility
Debt Instrument [Line Items]
Weighted average interest rate	5.49%	5.49%			5.49%
Repayments of debt					$ 16,556,000
Excess cash flow payment			$ 18,000,000		18,000,000
Optional prepayment		$ 5,444,000			5,444,000
Long-term debt	$ 315,000,000	315,000,000			315,000,000						$ 355,000,000
Line of Credit | Revolving Credit Facility
Debt Instrument [Line Items]
Long-term debt	$ 0	0			0
Revolving Credit Facility | Secured Debt | Term Loan Facility
Debt Instrument [Line Items]
Debt instrument face amount												400,000,000
Revolving Credit Facility | Line of Credit | Revolving Credit Facility
Debt Instrument [Line Items]
Line of credit, maximum borrowing capacity												75,000,000
Debt instrument, LIBOR interest rate	0.095%
Line of credit, remaining borrowing capacity	$ 75,000,000	75,000,000			75,000,000
Revolving Credit Facility | Line of Credit | Revolving Credit Facility | London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Basis spread on variable rate	2.50%
Swing Line Loan | Line of Credit | Revolving Credit Facility
Debt Instrument [Line Items]
Line of credit, maximum borrowing capacity												$ 15,000,000
Interest Rate Swap | Secured Debt
Debt Instrument [Line Items]
Derivative, notional amount	$ 275,000,000	$ 275,000,000			$ 275,000,000
Forecast | Secured Debt | Term Loan Facility
Debt Instrument [Line Items]
Periodic payments							$ 18,300,000	$ 22,300,000	$ 16,200,000	$ 24,700,000

Financial Instruments - Narrati

Financial Instruments - Narrative (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Derivative [Line Items]
Long-term debt	$ 332,335,000		$ 332,335,000		$ 375,397,000
Net loss recorded in accumulated other comprehensive income	(942,000)	$ 68,000	(2,102,000)	$ 9,179,000
Interest Rate Swap
Derivative [Line Items]
Net loss recorded in accumulated other comprehensive income			4,719,000
Secured Debt | Interest Rate Swap
Derivative [Line Items]
Derivative, notional amount	275,000,000		275,000,000
Secured Debt | Term Loan Facility
Derivative [Line Items]
Long-term debt	$ 315,000,000		$ 315,000,000		$ 355,000,000

Financial Instruments - Fair Va

Financial Instruments - Fair Value of the Interest Rate Derivative (Details) - Fair Value, Recurring - Interest Rate Swap - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Derivative [Line Items]
Other current liabilities	$ (3,794)	$ (4,427)
Other non-current liabilities	(1,108)	(2,629)
Total liabilities at fair value	(4,902)	(7,056)
Level 1
Derivative [Line Items]
Other current liabilities	0	0
Other non-current liabilities	0	0
Total liabilities at fair value	0	0
Level 2
Derivative [Line Items]
Other current liabilities	(3,794)	(4,427)
Other non-current liabilities	(1,108)	(2,629)
Total liabilities at fair value	(4,902)	(7,056)
Level 3
Derivative [Line Items]
Other current liabilities	0	0
Other non-current liabilities	0	0
Total liabilities at fair value	$ 0	$ 0

Financial Instruments - Schedul

Financial Instruments - Schedule of Total Value Recognized in Other Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2021	Mar. 31, 2021	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2021	Jun. 30, 2020
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Net gain (loss) recognized in OCI, before tax amount	$ (82)		$ (1,031)		$ 44	$ (10,205)
Net gain (loss) recognized in OCI, tax amount	19		232		(10)	2,296
Net gain (loss) recognized in OCI, net of tax amount	(63)		(799)		34	(7,909)
Net amount reclassified from AOCI into earnings, before tax amount	1,024		963		2,058	1,026
Net amount reclassified from AOCI into earnings, tax amount	(233)		(217)		(469)	(231)
Net amount reclassified from AOCI into earnings, net of tax amount	791		746		1,589	795
Change in OCI, before tax amount	942		(68)		2,102	(9,179)
Change in OCI, tax amount	(214)		15		(479)	2,065
Change in OCI, net of tax amount	$ 728	$ 895	$ (53)	$ (7,061)	1,623	$ (7,114)
Interest Rate Swap
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Change in OCI, before tax amount					(4,719)
Interest Expense | Interest Rate Swap
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Unrealized losses expected to be reclassified from AOCI within next 12 months					$ 3,611

Lease Obligations (Details)

Lease Obligations (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Lessee, Lease, Description [Line Items]
Lease termination period			10 years
Lease, Cost [Abstract]
Operating lease cost	$ 1,510	$ 2,075	$ 3,022	$ 4,234
Short-term lease cost	2,911	3,745	5,035	7,026
Finance lease cost:
Amortization of right-of-use assets	46	49	96	105
Interest on lease liabilities	5	7	11	15
Total finance lease cost	51	$ 56	107	120
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows from operating leases			2,980	4,336
Operating cash flows from finance leases			11	15
Financing cash flows from finance leases			96	105
Right-of-use assets obtained in exchange for lease obligations (noncash):
Operating leases			3,496	5,633
Finance leases			0	$ 0
Assets and Liabilities, Lessee [Abstract]
Operating lease right-of-use assets	16,609		16,609		$ 16,515
Current portion of long-term lease obligations	7,942		7,942		7,588
Long-term lease obligations	8,783		8,783		8,958
Total operating lease liabilities	16,725		16,725		16,546
Property and equipment, at cost	1,479		1,479		1,479
Accumulated depreciation	$ (806)		$ (806)		$ (702)
Finance Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]	Property and equipment, net ($9,539 and $6,010 related to VIEs)		Property and equipment, net ($9,539 and $6,010 related to VIEs)		Property and equipment, net ($9,539 and $6,010 related to VIEs)
Property and equipment, net	$ 673		$ 673		$ 777
Finance Lease, Liability, Current, Statement of Financial Position [Extensible List]	Current maturities of long-term debt ($6,793 and $6,793 related to VIEs)		Current maturities of long-term debt ($6,793 and $6,793 related to VIEs)		Current maturities of long-term debt ($6,793 and $6,793 related to VIEs)
Current maturities of long-term debt	$ 168		$ 168		$ 188
Finance Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]	Long-term debt ($79 and $53 related to VIEs)		Long-term debt ($79 and $53 related to VIEs)
Long-term debt	$ 295		$ 295		372
Total finance lease liabilities	$ 463		$ 463		$ 560
Weighted average remaining lease term: operating leases	3 years 4 months 24 days		3 years 4 months 24 days		3 years 2 months 12 days
Weighted average remaining lease term: financing leases	2 years 10 months 24 days		2 years 10 months 24 days		3 years 2 months 12 days
Weighted average discount rate: operating lease	5.50%		5.50%		5.70%
Weighted average discount rate: financing lease	4.20%		4.20%		4.20%
Operating Leases
2021 (excluding the six months ended June 30, 2021)	$ 3,715		$ 3,715
2022	6,510		6,510
2023	3,866		3,866
2024	1,820		1,820
2025	1,002		1,002
2026	928		928
Thereafter	628		628
Total lease payments	18,469		18,469
Less imputed interest	(1,744)		(1,744)
Total operating lease liabilities	16,725		16,725		$ 16,546
Finance Leases
2021 (excluding the six months ended June 30, 2021)	101		101
2022	161		161
2023	154		154
2024	77		77
2025	0		0
2026	0		0
Thereafter	0		0
Total lease payments	493		493
Less imputed interest	(30)		(30)
Total finance lease liabilities	$ 463		$ 463		$ 560
Minimum
Lessee, Lease, Description [Line Items]
Lease renewal term			1 month
Maximum
Lessee, Lease, Description [Line Items]
Lease renewal term			7 years

Commitments and Contingencies (

Commitments and Contingencies (Details)	Jun. 30, 2021	Jun. 30, 2020
Commitments and Contingencies Disclosure [Abstract]
Ownership interest in subsidiaries	50.00%	50.00%

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Operating Loss Carryforwards [Line Items]
Current tax expense	$ 1,027	$ 1,938	$ 1,645	$ 2,209
Deferred tax expense	7,152	5,310	11,294	6,223
Income tax expense	8,179	7,248	12,939	8,432
Cash paid for income taxes	$ 1,700	$ 0	$ 1,700	$ 44
Domestic Tax Authority
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards					$ 58,719
Operating loss carryforward expiration period			18 years
State and Local Jurisdiction
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards					$ 36,381
Minimum | State and Local Jurisdiction
Operating Loss Carryforwards [Line Items]
Operating loss carryforward expiration period			7 years
Maximum | State and Local Jurisdiction
Operating Loss Carryforwards [Line Items]
Operating loss carryforward expiration period			18 years

Stock Incentive Plan and Othe_3

Stock Incentive Plan and Other Equity Activity - Share Grants (Details) shares in Thousands	6 Months Ended
	Jun. 30, 2021$ / sharesshares
Class of Stock [Line Items]
Shares granted (in shares)	273
RSAs
Class of Stock [Line Items]
Shares granted (in shares)	26
Weighted Average Grant-Date Fair Value per Share (in dollars per share) | $ / shares	$ 23.22
RSUs
Class of Stock [Line Items]
Shares granted (in shares)	108
Weighted Average Grant-Date Fair Value per Share (in dollars per share) | $ / shares	$ 20.55
PSUs
Class of Stock [Line Items]
Shares granted (in shares)	139
Weighted Average Grant-Date Fair Value per Share (in dollars per share) | $ / shares	$ 20.54

Stock Incentive Plan and Othe_4

Stock Incentive Plan and Other Equity Activity - Share Issuances (Details) shares in Thousands	6 Months Ended
	Jun. 30, 2021shares
Class of Stock [Line Items]
Shares issued (in shares)	700
RSAs
Class of Stock [Line Items]
Shares issued (in shares)	26
RSUs
Class of Stock [Line Items]
Shares issued (in shares)	40
PSUs
Class of Stock [Line Items]
Shares issued (in shares)	621
ESPP
Class of Stock [Line Items]
Shares issued (in shares)	13

Stock Incentive Plan and Othe_5

Stock Incentive Plan and Other Equity Activity (Details) - USD ($) $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2021	Mar. 31, 2021	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2021	Jun. 30, 2020
Sale of Stock [Line Items]
Stock-based compensation expense	$ 2,015		$ 3,962		$ 3,850	$ 6,196
Shares withheld for taxes		$ (5,619)	(50)	$ (772)
Employee Stock Purchase Plan | ESPP
Sale of Stock [Line Items]
Stock-based compensation expense	$ 22		$ 18		$ 47	$ 36
Treasury Stock
Sale of Stock [Line Items]
Shares withheld for taxes (in shares)		16,000	3,000	46,000
Shares withheld for taxes		$ (296)	$ (32)	$ (668)
Treasury Stock | RSU/PSU
Sale of Stock [Line Items]
Shares withheld for taxes (in shares)	0				246,000
Shares withheld for taxes	$ 0				$ 5,619

Earnings Per Share (Details)

Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Numerator:
Net income attributable to Sterling common stockholders	$ 20,056	$ 18,210	$ 30,611	$ 21,325
Denominator:
Weighted average common shares outstanding - basic (in shares)	28,582	27,941	28,433	27,794
Shares for dilutive unvested stock and warrants (in shares)	472	16	445	93
Weighted average common shares outstanding - diluted (in shares)	29,054	27,957	28,878	27,887
Basic net income per share attributable to Sterling common stockholders (in dollars per share)	$ 0.70	$ 0.65	$ 1.08	$ 0.77
Diluted net income per share attributable to Sterling common stockholders (in dollars per share)	$ 0.69	$ 0.65	$ 1.06	$ 0.76

Supplemental Cash Flow Inform_3

Supplemental Cash Flow Information (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Supplemental Cash Flow Elements [Abstract]
Accounts receivable	$ (34,105)	$ (27,713)
Contracts in progress, net	26,008	22,964
Receivables from and equity in construction joint ventures	(1,358)	(3,200)
Other current and non-current assets	(8,448)	(306)
Accounts payable	38,308	(6,495)
Accrued compensation and other liabilities	3,936	10,453
Members' interest subject to mandatory redemption and undistributed earnings	3,703	4,748
Changes in operating assets and liabilities	$ 28,044	$ 451

Segment Information (Details)

Segment Information (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021USD ($)	Jun. 30, 2020USD ($)	Jun. 30, 2021USD ($)segment	Jun. 30, 2020USD ($)
Segment Reporting Information [Line Items]
Number of reportable segments | segment			3
Revenues	$ 401,666	$ 400,038	$ 716,982	$ 696,726
Operating Income	32,720	33,046	55,475	45,149
Acquisition related costs	0	(139)	0	(612)
Operating Segments
Segment Reporting Information [Line Items]
Revenues	401,666	400,038	716,982	696,726
Operating Income	32,720	33,185	55,475	45,761
Heavy Civil
Segment Reporting Information [Line Items]
Revenues	203,153	220,448	350,207	376,063
Heavy Civil | Operating Segments
Segment Reporting Information [Line Items]
Revenues	203,153	220,448	350,207	376,063
Operating Income	4,404	3,896	5,494	274
Specialty Services
Segment Reporting Information [Line Items]
Revenues	151,904	135,703	275,992	240,426
Specialty Services | Operating Segments
Segment Reporting Information [Line Items]
Revenues	151,904	135,703	275,992	240,426
Operating Income	22,907	23,246	39,084	34,360
Residential
Segment Reporting Information [Line Items]
Revenues	46,609	43,887	90,783	80,237
Residential | Operating Segments
Segment Reporting Information [Line Items]
Revenues	46,609	43,887	90,783	80,237
Operating Income	$ 5,409	$ 6,043	$ 10,897	$ 11,127