Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
OPERATING ACTIVITIES
Net income	$ 62,971	$ 141,907	$ 8,122
Adjustments to reconcile net income to cash used in operating activities:
Depreciation and amortization	133,969	125,100	111,273
Deferred income taxes	21,838	(35,804)	96,224
(Gain) loss on sale of business units, property and equipment	(1,377)	845	206
Adjustment to carrying value of assets	6,625	1,230	1,479
Equity earnings in non-consolidated entities	0	(738)	(3,639)
Amortization of deferred financing costs	1,971	2,107	9,422
Loss on extinguishment of debt	0	0	23,262
Non-cash gain on previously held shares of an equity investment	0	(20,767)	0
Stock-based compensation	13,315	15,052	19,785
Contributions to U.S. pension plan	(7,760)	(4,125)	(10,000)
Amortization of U.S. pension expense	8,919	9,314	12,680
Other items, net	(3,320)	2,263	(6,873)
Net change in operating assets and liabilities, net of effect of acquisitions:
Accounts receivable	8,426	16,507	1,295
Inventories	4,190	(33,092)	(30,518)
Other assets	6,938	(18,966)	(5,673)
Accounts payable and accrued expenses	37,611	39,540	26,740
Change in short term and long-term tax liabilities	8,393	(20,720)	12,008
Net cash provided by operating activities	302,709	219,653	265,793
INVESTING ACTIVITIES
Purchases of property and equipment	(101,506)	(97,399)	(59,599)
Proceeds from sale of business units, property and equipment	8,632	1,973	2,713
Purchase of intangible assets	(34,686)	(21,301)	(3,450)
Purchases of businesses, net of cash acquired	(57,799)	(167,688)	(131,448)
Cash received for notes receivable	411	274	1,991
Net cash used in investing activities	(184,948)	(284,141)	(189,793)
FINANCING ACTIVITIES
Change in long-term debt	13,101	70,468
Change in long-term debt			(389,665)
Payments of notes payable	0	0	205
Employee note repayments	0	39	26
Contingent consideration for acquisitions	0	(3,701)	0
Common stock issued for exercise of options	1,977	201	1,029
Common stock repurchased	(19,994)	(125,030)	0
Payments to tax authorities for employee share-based compensation	(1,495)	(9,452)	(25,335)
Proceeds from sale of common stock, net of underwriting fees and commissions	0	0	480,306
Payments associated with initial public offering	0	0	(2,066)
Net cash (used in) provided by financing activities	(6,411)	(67,475)	64,090
Effect of foreign currency exchange rates on cash	903	(6,648)	12,692
Net increase (decrease) in cash and cash equivalents	112,253	(138,611)	152,782
Cash, cash equivalents and restricted cash, beginning	117,623	256,234	103,452
Cash, cash equivalents and restricted cash, ending	$ 229,876	$ 117,623	$ 256,234