CONDENSED CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY - USD ($) shares in Thousands, $ in Thousands	Total	Preferred Stock	Common Stock	Additional Paid-In Capital	Retained Earnings	Accumulated Other Comprehensive Loss	Common Stock Held in Treasury
Balance at beginning of period (shares) at Dec. 31, 2015		0	40,288				12,052
Balance at beginning of period (value) at Dec. 31, 2015	$ 431,382	$ 0	$ 403	$ 202,393	$ 643,604	$ (78,410)	$ (336,608)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares issued under share-based compensation plan (shares)			7
Shares issued under share-based compensation plan (value)	0		$ 0
Share-based compensation expense (value)	1,021			1,021
Net income	24,847				24,847
Dividends paid	(7,061)				(7,061)
Currency translation adjustment	(16,703)					(16,703)
Balance at end of period (shares) at Jun. 30, 2016		0	40,295				12,052
Balance at end of period (value) at Jun. 30, 2016	433,486	$ 0	$ 403	203,414	661,390	(95,113)	$ (336,608)
Balance at beginning of period (shares) at Dec. 31, 2016		0	49,276				769
Balance at beginning of period (value) at Dec. 31, 2016	1,449,986	$ 0	$ 493	1,217,969	387,401	(119,806)	$ (36,071)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares issued under share-based compensation plan (shares)			0				10
Shares issued under share-based compensation plan (value)	0		$ 0	(440)			$ 440
Exercise of stock options (shares)			0				13
Exercise of stock options (value)	307		$ 0	(242)			$ 549
Share-based compensation expense (value)	1,535			1,535
Net income	47,884				47,884
Dividends paid	(18,348)				(18,348)
Currency translation adjustment	36,342					36,342
Repurchases of treasury stock (shares)							518
Repurchases of treasury stock (value)	(26,274)						$ (26,274)
Balance at end of period (shares) at Jun. 30, 2017		0	49,276				1,264
Balance at end of period (value) at Jun. 30, 2017	$ 1,491,432	$ 0	$ 493	$ 1,218,822	$ 416,937	$ (83,464)	$ (61,356)