Condensed Consolidated Statements Of Stockholders' Equity - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Loss	Treasury Stock
Beginning Balance at Dec. 31, 2015	$ 639,184	$ 876	$ 237,291	$ 1,446,193	$ (208,806)	$ (836,370)
Beginning Balance (in shares) at Dec. 31, 2015		60,393
Increase (Decrease) in Stockholders' Equity
Net income	26,572			26,572
Other comprehensive income	11,350				11,350
Dividends declared on common stock	(10,456)			(10,456)
Stock compensation expense	3,059		3,059
Adoption of accounting standard update related to stock compensation accounting	525		598	(73)
Net issuance of treasury stock for vested restricted stock units (in shares)		75
Net issuance of treasury stock for vested restricted stock units	(2,204)		(744)			(1,460)
Ending Balance at Mar. 31, 2016	668,030	$ 876	240,204	1,462,236	(197,456)	(837,830)
Ending Balance (in shares) at Mar. 31, 2016		60,468
Beginning Balance at Dec. 31, 2016	469,415	$ 876	249,763	1,558,594	(223,856)	(1,115,962)
Beginning Balance (in shares) at Dec. 31, 2016		55,051
Increase (Decrease) in Stockholders' Equity
Net income	23,232			23,232
Other comprehensive income	7,746				7,746
Dividends declared on common stock	(10,115)			(10,115)
Stock compensation expense	3,279		3,279
Net issuance of treasury stock for vested restricted stock units (in shares)		91
Net issuance of treasury stock for vested restricted stock units	(3,231)		(914)			(2,317)
Ending Balance at Mar. 31, 2017	$ 490,326	$ 876	$ 252,128	$ 1,571,711	$ (216,110)	$ (1,118,279)
Ending Balance (in shares) at Mar. 31, 2017		55,142