Consolidated Statements of Stockholders' Deficit - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid - in Capital [Member]	Retained Deficit [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Treasury Stock [Member]
BALANCE at Dec. 31, 2012	$ (1,249,686)	$ 62	$ 1,720,639	$ (2,941,948)	$ (23,131)	$ (5,308)
Net income	143,202			143,202
Dividends declared (cash dividend/$0.675 - 2013, 0.90 - 2014, 0.90 - 2015 per share)	(56,443)			(56,443)
Other comprehensive income (loss), net of tax of (6,700 - 2013, 13,662 - 2014, 19,903 - 2015)	10,931				10,931
Executive Deferred Compensation Plan activity, net (63,773 - 2013, 62,489 - 2014, 204,323 - 2015 shares distributed)	3,301		3,301
Issuance of common stock in connection with our initial public offering (21,275,000 shares)	401,033	21	401,012
Initial public offering costs	(2,967)		(2,967)
Stock options exercised including related tax benefits (218,872 - 2013, 112,216 - 2014, 413,008 - 2015 shares)	2,159	1	2,158
Share based compensation	8,298		8,298
BALANCE at Dec. 31, 2013	(740,172)	84	2,132,441	(2,855,189)	(12,200)	(5,308)
Net income	158,405			158,405
Dividends declared (cash dividend/$0.675 - 2013, 0.90 - 2014, 0.90 - 2015 per share)	(75,991)			(75,991)
Other comprehensive income (loss), net of tax of (6,700 - 2013, 13,662 - 2014, 19,903 - 2015)	(25,306)				(25,306)
Executive Deferred Compensation Plan activity, net (63,773 - 2013, 62,489 - 2014, 204,323 - 2015 shares distributed)	3,474		3,474
Stock options exercised including related tax benefits (218,872 - 2013, 112,216 - 2014, 413,008 - 2015 shares)	766		766
Share issued from the Employee Stock Purchase Plan (271,255 - 2014, 286,141 - 2015 shares)	6,037		6,037
Share based compensation	13,146		13,146
BALANCE at Dec. 31, 2014	(659,641)	84	2,155,864	(2,772,775)	(37,506)	(5,308)
Net income	241,840			241,840
Dividends declared (cash dividend/$0.675 - 2013, 0.90 - 2014, 0.90 - 2015 per share)	(76,480)			(76,480)
Other comprehensive income (loss), net of tax of (6,700 - 2013, 13,662 - 2014, 19,903 - 2015)	(35,230)				(35,230)
Purchase of stock at cost (2,000,000 shares)	(59,957)					(59,957)
Executive Deferred Compensation Plan activity, net (63,773 - 2013, 62,489 - 2014, 204,323 - 2015 shares distributed)	3,638		3,638
Stock options exercised including related tax benefits (218,872 - 2013, 112,216 - 2014, 413,008 - 2015 shares)	5,641	1	5,640
Share issued from the Employee Stock Purchase Plan (271,255 - 2014, 286,141 - 2015 shares)	7,184		7,184
Share based compensation	20,867		20,867
BALANCE at Dec. 31, 2015	$ (552,138)	$ 85	$ 2,193,193	$ (2,607,415)	$ (72,736)	$ (65,265)