Consolidated Statements of Stockholders' Equity (USD $) In Thousands, unless otherwise specified	Total	Common Stock	Paid-In Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	Treasury Stock
BALANCE at Dec. 31, 2011	$ 725,147	$ 805	$ 94,396	$ 779,994	$ (5,170)	$ (144,878)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Comprehensive income	104,048	0	0	103,034	1,014	0
Dividends on common stock	(124,411)	0	0	(124,411)	0	0
Equity compensation activity, including excess tax benefits	5,511	0	(1,541)	0	0	7,052
Non-cash equity compensation expense	4,602	0	4,602	0	0	0
BALANCE at Dec. 31, 2012	714,897	805	97,457	758,617	(4,156)	(137,826)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Comprehensive income	86,310	0	0	86,785	(475)	0
Purchases of common stock	(20,060)	0	0	0	0	(20,060)
Dividends on common stock	(14,560)	0	0	(14,560)	0	0
Equity compensation activity, including excess tax benefits	1,123	0	(3,732)	0	0	4,855
Non-cash equity compensation expense	4,809	0	4,809	0	0	0
BALANCE at Dec. 31, 2013	772,519	805	98,534	830,842	(4,631)	(153,031)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Comprehensive income	93,906	0	0	98,650	(4,744)	0
Purchases of common stock	(30,587)	0	0	0	0	(30,587)
Dividends on common stock	(14,407)	0	0	(14,407)	0	0
Equity compensation activity, including excess tax benefits	6,359	0	(2,801)	0	0	9,160
Non-cash equity compensation expense	6,070	0	6,070	0	0	0
BALANCE at Dec. 31, 2014	$ 833,860	$ 805	$ 101,803	$ 915,085	$ (9,375)	$ (174,458)