CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Cash flows from operating activities:
Net income	$ 83,381	$ 85,006	$ 58,759
Adjustments to reconcile net income to net cash flows provided by operating activities:
Depreciation and amortization of property and equipment	49,161	43,894	42,867
Amortization of intangible assets	9,009	2,311	3,586
Stock-based compensation expense	7,922	7,496	5,688
Deferred income taxes	9,573	6,281	(2,641)
Gain on sale of property and equipment	(2,378)	(3,098)	(2,813)
Other non-cash items	2,294	1,892	1,951
Changes in operating assets and liabilities:
Accounts receivable, net	(86,939)	10,659	2,903
Contract assets, net	(64,421)	(39,266)	31,360
Receivable for insurance claims in excess of deductibles	(14)	(4,619)	(1,511)
Prepaid expenses and other assets	1,640	(25,320)	(15,458)
Accounts payable	109,008	34,348	(43,079)
Contract liabilities	58,001	9,573	52,918
Accrued self-insurance	4,999	5,233	3,010
Other liabilities	(13,752)	2,838	37,627
Net cash flows provided by operating activities	167,484	137,228	175,167
Cash flows from investing activities:
Proceeds from sale of property and equipment	1,990	3,062	3,429
Cash paid for acquisitions, net of cash acquired	(110,660)	0	0
Purchases of property and equipment	(77,056)	(52,361)	(44,355)
Net cash flows used in investing activities	(185,726)	(49,299)	(40,926)
Cash flows from financing activities:
Net borrowings (repayments) under revolving lines of credit	12,915	0	(103,820)
Payment of principal obligations under equipment notes	(1,047)	(24,917)	(32,584)
Payment of principal obligations under finance leases	(1,592)	(336)	(1,238)
Borrowings under equipment notes	24,184	0	0
Proceeds from exercise of stock options	40	498	749
Repurchase of common stock	(36,981)	0	0
Payments related to tax withholding for stock-based compensation	(6,791)	(3,352)	(652)
Other financing activities	0	12	13,249
Net cash flows used in financing activities	(9,272)	(28,095)	(124,296)
Effect of exchange rate changes on cash	(3,538)	(410)	326
Net increase (decrease) in cash and cash equivalents	(31,052)	59,424	10,271
Cash and cash equivalents:
Beginning of period	82,092	22,668	12,397
End of period	51,040	82,092	22,668
Cash paid during the period for:
Income taxes payments	20,462	30,009	24,185
Interest payments	2,736	1,444	4,071
Noncash investing activities:
Acquisition of property and equipment for which payment is pending	$ 2,218	$ 4,120	$ 349