Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Operating activities
Net income (loss)	$ (6,585)	$ 88,836	$ 966
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	12,747	9,488	10,582
Amortization	44,251	16,694	6,234
Provision for doubtful accounts	(2,296)	(3,530)	4,078
Stock-based compensation	5,904	3,930	5,414
Deferred income taxes	(17,691)	11,919	71
Amortization of deferred financing costs and debt discount	2,730	921	293
Equity in net (income) loss of investee	53,092	(8,860)	29,685
Reduction of right-of-use assets	11,330	9,238	10,133
Changes in operating assets and liabilities, net of effects of acquisitions:
Accounts receivable and other receivables	(11,453)	55,885	(29,928)
Prepaid expenses and other assets	(7,587)	(12,609)	(9,502)
Income tax refunds on sale of business	0	(10,273)	30,822
Insurance programs	5,426	2,056	809
Accrued contract payables	107,698	158,182	5,950
Accounts payable and accrued expenses	(23,460)	33,328	(10,094)
Accrued transportation costs	23,620	(7,389)	2,175
Deferred revenue	1,239	(176)	(1,298)
Other long-term liabilities	(12,125)	795	4,550
Net cash provided by operating activities	186,840	348,435	60,940
Investing activities
Purchase of property and equipment	(21,316)	(12,150)	(10,858)
Acquisitions, net of cash acquired	(664,309)	(622,862)	0
Net cash used in investing activities	(685,625)	(635,012)	(10,858)
Financing activities
Proceeds from debt	625,000	737,000	12,000
Repayment of debt	(125,000)	(237,000)	(12,000)
Repurchase of common stock, for treasury	(39,994)	(10,186)	(6,797)
Payment of debt issuance costs	(13,486)	(15,633)	0
Proceeds from common stock issued pursuant to stock option exercise	3,227	25,413	11,142
Restricted stock surrendered for employee tax payment	(896)	(267)	0
Preferred stock redemption payment	0	(88,771)	0
Preferred stock dividends	0	(1,987)	(4,403)
Other financing activities	0	(309)	(718)
Net cash provided by (used in) financing activities	448,851	408,260	(776)
Net change in cash, cash equivalents and restricted cash	(49,934)	121,683	49,306
Cash, cash equivalents and restricted cash at beginning of period	183,356	61,673	12,367
Cash, cash equivalents and restricted cash at end of period	133,422	183,356	61,673
Supplemental cash flow information
Cash paid for interest	32,178	2,192	1,261
Cash paid (received) for income taxes	13,021	21,766	(30,037)
Assets acquired under operating leases	24,152	19,992	6,787
Acquisitions:
Purchase price	678,655	644,044	0
Less:
Cash acquired	(14,346)	(21,182)	0
Acquisitions, net of cash acquired	$ 664,309	$ 622,862	$ 0