CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS $ in Thousands	6 Months Ended
	Jun. 30, 2022 USD ($)	Jun. 30, 2021 USD ($)
Cash flows from operating activities:
Net income	$ 48,480	$ 42,143
Adjustments to reconcile net income to net cash provided by operating activities (net of effect of acquisitions):
Depreciation and amortization	40,778	51,702
Stock-based compensation expense	3,995	7,485
Gain on sale of property and equipment	(9,972)	(7,110)
Gain on sale and leaseback transaction	(40,084)
Unrealized gain on interest rate swap	(4,571)	(2,255)
Other non-cash items	579	566
Changes in assets and liabilities:
Accounts receivable	(105,690)	11,357
Contract assets	(63,640)	(27,733)
Other current assets	(54,142)	(19,448)
Other long-term assets	(13,118)	(181)
Accounts payable	62,877	6,900
Contract liabilities	9,798	(56,688)
Operating lease assets and liabilities, net	(1,088)	(1,831)
Accrued liabilities	34,932	6,266
Other long-term liabilities	(247)	(5,010)
Net cash (used in) provided by operating activities	(91,113)	6,163
Cash flows from investing activities:
Purchase of property and equipment	(65,815)	(62,755)
Proceeds from sale of assets	11,184	10,534
Proceeds from sale and leaseback transaction, net of related expenses	49,887
Cash paid for acquisitions, net of cash acquired	(39,631)	(606,974)
Net cash used in investing activities	(44,375)	(659,195)
Cash flows from financing activities:
Proceeds from issuance of long-term debt	30,000	421,000
Payments on long-term debt	(55,957)	(79,515)
Proceeds from issuance of common stock		178,712
Debt issuance costs		(4,876)
Dividends paid	(6,390)	(6,110)
Purchase of common stock	(3,370)
Other	(3,083)	(4,959)
Net cash provided by financing activities	26,200	504,252
Effect of exchange rate changes on cash, cash equivalents and restricted cash	(45)	585
Net change in cash, cash equivalents and restricted cash	(109,333)	(148,195)
Cash, cash equivalents and restricted cash at beginning of the period	205,643	330,975
Cash, cash equivalents and restricted cash at end of the period	96,310	182,780
SUPPLEMENTAL DISCLOSURES OF CASH FLOW INFORMATION
Cash paid for interest	11,586	11,234
Cash paid for income taxes, net of refunds received	2,145	17,609
Leased assets obtained in exchange for new operating leases	12,865	10,673
SUPPLEMENTAL DISCLOSURES OF NONCASH INVESTING AND FINANCING ACTIVITIES
Dividends declared and not yet paid	3,192	3,224
Revolving Credit Facility
Cash flows from financing activities:
Borrowings under revolving line of credit or credit facility	65,000	100,000
Payments on revolving line of credit or credit facility		$ (100,000)
Canadian Credit Facility
Cash flows from financing activities:
Borrowings under revolving line of credit or credit facility	12,379
Payments on revolving line of credit or credit facility	$ (12,379)