UNAUDITED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Cash flows from operating activities:
Net income	$ 41,147	$ 23,317
Adjustments to reconcile net income to net cash flows provided by operating activities:
Depreciation and amortization of property and equipment	22,172	21,324
Amortization of intangible assets	1,156	2,431
Stock-based compensation expense	3,435	2,173
Deferred income taxes	481	537
Gain on sale of property and equipment	(1,794)	(1,489)
Other non-cash items	1,370	267
Changes in operating assets and liabilities, net of acquisitions:
Accounts receivable, net	(10,098)	46,353
Contract assets, net	(10,855)	(7,658)
Receivable for insurance claims in excess of deductibles	304	4,934
Other assets	10,389	7,198
Accounts payable	47,772	(38,342)
Contract liabilities	(21,433)	23,271
Accrued self insurance	1,869	(5,843)
Other liabilities	2,647	19,450
Net cash flows provided by operating activities	88,562	97,923
Cash flows from investing activities:
Proceeds from sale of property and equipment	1,637	1,633
Purchases of property and equipment	(20,997)	(16,938)
Net cash flows used in investing activities	(19,360)	(15,305)
Cash flows from financing activities:
Net repayments under revolving lines of credit	0	(70,423)
Payment of principal obligations under equipment notes	(20,635)	(13,433)
Payment of principal obligations under finance leases	(376)	(616)
Proceeds from exercise of stock options	429	82
Repurchase of common shares	(3,352)	(425)
Other financing activities	12	49
Net cash flows used in financing activities	(23,922)	(84,766)
Effect of exchange rate changes on cash	374	(258)
Net increase in cash and cash equivalents	45,654	(2,406)
Cash and cash equivalents:
Beginning of period	22,668	12,397
End of period	$ 68,322	$ 9,991