CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Cash flows from operating activities
Net income (loss)	$ (376,952)	$ 23,523	$ 49,395
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Depreciation and amortization	56,565	58,964	56,842
Deferred income taxes	15,097	(10,398)	5,350
(Income) loss from discontinued operations	1,847	81	(1,481)
Restructuring charges	13,440	8,380	1,587
Legal settlement		8,500
Impairment charges (recoveries)	203,076	5,346	(35)
(Gains) losses on dispositions of property and other assets	(14,935)	(1,475)	473
Share-based compensation expense	2,653	7,190	4,870
Multi-employer pension plan withdrawal	462	15,693
Other non-cash items, net	8,056	3,791	4,306
Change in operating assets and liabilities (excluding the impact of acquisitions):
Receivables	106,082	(16,959)	(6,200)
Inventories	8,644	(328)	(1,573)
Current contract costs	16,279	(6,333)	(4,976)
Accounts payable	(88,251)	9,726	(1,645)
Restructuring liabilities	(7,427)	(6,047)	(1,716)
Accrued compensation	(26,375)	6,853	(12,818)
Contract liabilities	(31,585)	16,796	3,677
Income taxes payable	770	195	(7,696)
Other assets and liabilities, net	32,306	(15,359)	2,235
Net cash (used in) provided by operating activities	(80,248)	108,139	90,595
Cash flows from investing activities
Capital expenditures	(53,567)	(76,147)	(83,345)
Cash surrender value of life insurance policies	24,767
Cash paid for acquisitions, net		(90,992)	(4,628)
Proceeds from dispositions of property and other assets	22,027	1,583	925
Net cash used in investing activities	(6,773)	(165,556)	(87,048)
Cash flows from financing activities
Proceeds from borrowings	225,422	200,473	146,580
Payments on debt and finance lease obligations	(275,327)	(115,708)	(128,211)
Dividends paid on common stock	(4,064)	(8,094)	(8,154)
Distributions to noncontrolling interest	(1,526)	(407)
Payments of debt issuance costs	(1,585)	(39)	(1,823)
Payment of payroll taxes on stock-based compensation through shares withheld or repurchased	(1,688)	(3,046)	(1,209)
Common stock purchased for treasury	(2,785)		(17,174)
Proceeds from issuance of Convertible Series A Preferred Stock, net of issuance costs	125,763
Proceeds from exercise of stock options	2,077	293	84
Net cash provided by (used in) financing activities	66,287	73,472	(9,907)
Effect of exchange rate changes on cash, cash equivalents, and restricted cash	701	1,050	(2,470)
Net change in cash, cash equivalents, and restricted cash	(20,033)	17,105	(8,830)
Cash, cash equivalents, and restricted cash, beginning of year	62,004	44,899	53,729
Cash, cash equivalents, and restricted cash, end of year	$ 41,971	$ 62,004	$ 44,899