CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Cash flows from operating activities:
Net income	$ 90,990	$ 83,381	$ 85,006
Adjustments to reconcile net income to net cash flows provided by operating activities:
Depreciation and amortization of property and equipment	54,231	49,161	43,894
Amortization of intangible assets	4,907	9,009	2,311
Stock-based compensation expense	8,376	7,922	7,496
Deferred income taxes	2,056	9,573	6,281
Gain on sale of property and equipment	(4,214)	(2,378)	(3,098)
Other non-cash items	96	2,294	1,892
Changes in operating assets and liabilities:
Accounts receivable, net	(48,527)	(86,939)	10,659
Contract assets, net	(119,246)	(64,421)	(39,266)
Receivable for insurance claims in excess of deductibles	1,529	(14)	(4,619)
Prepaid expenses and other assets	560	1,640	(25,320)
Accounts payable	37,250	109,008	34,348
Contract liabilities	13,151	58,001	9,573
Accrued self-insurance	17	4,999	5,233
Other liabilities	29,840	(13,752)	2,838
Net cash flows provided by operating activities	71,016	167,484	137,228
Cash flows from investing activities:
Proceeds from sale of property and equipment	5,608	1,990	3,062
Cash paid for acquisitions, net of cash acquired	0	(110,660)	0
Purchases of property and equipment	(84,736)	(77,056)	(52,361)
Net cash flows used in investing activities	(79,128)	(185,726)	(49,299)
Cash flows from financing activities:
Borrowings under revolving lines of credit	562,901	198,697	0
Repayments under revolving lines of credit	(562,615)	(185,782)	0
Payment of principal obligations under equipment notes	(4,598)	(1,047)	(24,917)
Payment of principal obligations under finance leases	(1,143)	(1,592)	(336)
Borrowings under equipment notes	0	24,184	0
Proceeds from exercise of stock options	20	40	498
Debt refinancing costs	(2,129)	0	0
Repurchase of common stock	(2,868)	(36,981)	0
Payments related to tax withholding for stock-based compensation	(7,936)	(6,791)	(3,352)
Other financing activities	0	0	12
Net cash flows used in financing activities	(18,368)	(9,272)	(28,095)
Effect of exchange rate changes on cash	339	(3,538)	(410)
Net increase (decrease) in cash and cash equivalents	(26,141)	(31,052)	59,424
Cash and cash equivalents:
Beginning of period	51,040	82,092	22,668
End of period	24,899	51,040	82,092
Cash paid during the period for:
Income taxes payments	23,949	20,462	30,009
Interest payments	4,145	2,736	1,444
Noncash investing activities:
Acquisition of property and equipment for which payment is pending	$ 8,474	$ 2,218	$ 4,120