Consolidated Statements of Stockholders' Equity (USD $) In Thousands, unless otherwise specified	Total	Common Stock [Member]	Paid-in Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Treasury Stock [Member]
BALANCE at Dec. 31, 2009	$ 704,650	$ 805	$ 92,389	$ 778,890	$ (5,556)	$ (161,878)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Comprehensive income	82,175	0	0	80,039	2,136	0
Dividends on common stock	(130,713)	0	0	(130,713)	0	0
Stock based compensation activity, including excess tax benefits	11,402	0	(1,978)	0	0	13,380
Stock-based compensation expense	1,461	0	1,461	0	0	0
BALANCE at Dec. 31, 2010	668,975	805	91,872	728,216	(3,420)	(148,498)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Comprehensive income	101,007	0	0	102,757	(1,750)	0
Dividends on common stock	(50,979)	0	0	(50,979)	0	0
Stock based compensation activity, including excess tax benefits	3,545	0	(75)	0	0	3,620
Stock-based compensation expense	2,599	0	2,599	0	0	0
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
Stock based compensation activity, including excess tax benefits	5,511	0	(1,541)	0	0	7,052
Stock-based 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)