CONSOLIDATED STATEMENTS OF CHANGES IN EQUITY - USD ($) $ in Thousands	Total	Cumulative Effect, Period of Adoption, Adjustment	Common Stock Issued	Treasury Stock	Additional Paid-in Capital	Retained Earnings	Retained Earnings Cumulative Effect, Period of Adoption, Adjustment	Accumulated Other Comprehensive Income (Loss)	Accumulated Other Comprehensive Income (Loss) Cumulative Effect, Period of Adoption, Adjustment	Noncontrolling Interests
Balances at Dec. 31, 2017	$ 215,165	$ 2,374	$ 141,110	$ (762,079)	$ 180,201	$ 1,157,801	$ 3,894	$ (546,582)	$ (1,520)	$ 44,714
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	145,013					137,057				7,956
Cash dividends declared:
Noncontrolling interests	(5,534)									(5,534)
Total other comprehensive income (loss)	(21,505)							(19,005)		(2,500)
Purchase of subsidiary shares from noncontrolling interest	477				0					477
Stock appreciation rights exercised	(282)		50	(282)	(50)
Vesting of restricted stock units and other stock grants	(3,449)		682	(3,449)	(682)
Treasury shares repurchased	(30,011)			(30,011)
Amortization of unearned stock-based compensation, net of forfeitures	11,128				11,128
Balances at Dec. 31, 2018	313,376	$ 0	141,842	(795,821)	190,597	1,298,752	$ 21,429	(567,107)	$ (21,429)	45,113
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	512,218					503,919				8,299
Cash dividends declared:
Noncontrolling interests	(4,693)									(4,693)
Total other comprehensive income (loss)	(58)							914		(972)
Sale of investment in consolidated subsidiary	4,026									4,026
Strategic venture exit	(3,694)									(3,694)
Stock appreciation rights exercised	(117)		20	(117)	(20)
Vesting of restricted stock units and other stock grants	(2,882)		402	(2,882)	(402)
Vesting of performance share units	(8,248)		1,136	(8,235)	(1,149)
Treasury shares repurchased	(31,838)			(31,838)
Amortization of unearned stock-based compensation, net of forfeitures	11,569				11,569
Balances at Dec. 31, 2019	789,659		143,400	(838,893)	200,595	1,824,100		(587,622)		48,079
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(21,975)					(26,341)				4,366
Cash dividends declared:
Noncontrolling interests	(2,978)									(2,978)
Total other comprehensive income (loss)	(55,307)							(58,119)		2,812
Purchase of subsidiary shares from noncontrolling interest	(561)				4,527					3,966
Stock appreciation rights exercised	(24)		11	(24)	(11)
Vesting of restricted stock units and other stock grants	(1,108)		288	(1,108)	(288)
Vesting of performance share units	(3,205)		589	(3,205)	(589)
Amortization of unearned stock-based compensation, net of forfeitures	8,898				8,898
Balances at Dec. 31, 2020	$ 713,399		$ 144,288	$ (843,230)	$ 204,078	$ 1,797,759		$ (645,741)		$ 56,245