CONSOLIDATED STATEMENTS OF CHANGES IN EQUITY - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional paid-in capital [Member]	Retained earnings [Member]	Treasury stock [Member]	Treasury stock reserved for contractual obligations	Accumulated other comprehensive income (loss) [Member]	Parent [Member]	Noncontrolling interest [Member]
Balance, Beginning at Dec. 31, 2012	$ 632,362	$ 0	$ 507,199	$ 173,407	$ (16,445)	$ (1,075)	$ (56,469)	$ 606,617	$ 25,745
Balance, Beginning (in shares) at Dec. 31, 2012		48,562,204
Net income (loss)	29,687			35,205				35,205	(1,571)
Net Income (Loss) Attributable to Nonredeemable Noncontrolling Interest	33,634
CTA, net of tax	(24,287)						(20,071)	(20,071)	(3,184)
Temporary Equity, Foreign Currency Translation Adjustments	(23,255)
Pension liability adjustments, net of tax	14,749						14,749	14,749
Unrealized gain (loss) on investments, net of tax	(3)						(3)	(3)
Dividends on common stock	(1,071)			1,071				1,071
Note conversion	45,903		45,903					45,903
Note conversion (in shares)		4,903,044
Exercise of stock options	1,001		459		$ 542			1,001
Exercise of stock options (in shares)		60,417
Acquisitions	168		0					0	168
Acquisitions (in shares)		0
Capital contribution from noncontrolling interest	79,592
Noncontrolling Interest, Change in Redemption Value	0
Stock-based compensation	4,815		4,815					4,815
Adjustments to Additional Paid in Capital, Income Tax Deficiency from Share-based Compensation	(68)		(68)					(68)
Issuance of treasury stock under 401(k) plan	646		329		$ 317			646
Issuance of treasury stock under 401(k) plan (in shares)		35,207
Balance, Ending at Dec. 31, 2013	708,881		558,637	207,541	(15,586)	(1,075)	(61,794)	687,723	21,158
Balance, Ending (in shares) at Dec. 31, 2013		53,560,872
Net income (loss)	(130,425)			(80,461)				(80,461)	(12,320)
Net Income (Loss) Attributable to Nonredeemable Noncontrolling Interest	(92,781)
CTA, net of tax	(63,424)						(44,554)	(44,554)	(1,467)
Temporary Equity, Foreign Currency Translation Adjustments	(46,021)
Pension liability adjustments, net of tax	5,129						(5,129)	(5,129)
Dividends on common stock	(1,073)			1,073				(1,073)
Note conversion	0
Restricted stock awards	0		(1,250)		1,250			0
Restricted stock awards (in shares)		139,250
Exercise of stock options	141		60		81			141
Exercise of stock options (in shares)		8,971
Acquisitions	(1,202)		(49)				(1,153)	(1,202)
Capital contribution from noncontrolling interest	0
Noncontrolling Interest, Change in Redemption Value	(49,277)		(49,277)					(49,277)
Stock-based compensation	5,360		5,360					5,360
Adjustments to Additional Paid in Capital, Income Tax Deficiency from Share-based Compensation	(672)		(672)					(672)
Issuance of treasury stock under 401(k) plan	639		281		358			639
Issuance of treasury stock under 401(k) plan (in shares)		39,935
Balance, Ending at Dec. 31, 2014	518,866	$ 0	513,090	126,007	(13,897)	(1,075)	(112,630)	511,495	7,371
Balance, Ending (in shares) at Dec. 31, 2014		53,749,028.000
Net income (loss)	(90,287)			(75,633)				(75,633)	(7,640)
Net Income (Loss) Attributable to Nonredeemable Noncontrolling Interest	(83,273)
CTA, net of tax	(79,196)						(74,459)	(74,459)
Temporary Equity, Foreign Currency Translation Adjustments	(74,524)								(65)
Pension liability adjustments, net of tax	(662)						$ (662)	(662)
Dividends on common stock	(1,077)			1,077				1,077
Note conversion	0
Restricted stock awards	0		(777)		777			0
Restricted stock awards (in shares)		86,500
Exercise of stock options	$ 145		$ 33		$ 112			145
Exercise of stock options (in shares)	(12,500)	12,500
Acquisitions	$ (42)							0	(42)
Acquisitions (in shares)
Capital contribution from noncontrolling interest	0
Noncontrolling Interest, Change in Redemption Value	(17,668)		$ (17,668)					(17,668)	0
Stock-based compensation	2,335		2,335					2,335
Adjustments to Additional Paid in Capital, Income Tax Deficiency from Share-based Compensation	0
Issuance of treasury stock under 401(k) plan	583		(5)		$ 588			583
Issuance of treasury stock under 401(k) plan (in shares)		65,481
Balance, Ending at Dec. 31, 2015	$ 344,683	$ 0	$ 497,008	$ 49,297	$ (12,420)	$ (1,075)	$ (187,751)	$ 345,059	$ (376)
Balance, Ending (in shares) at Dec. 31, 2015		53,913,509