Consolidated Statements of Changes in Shareholders' Equity (USD $) In Thousands, unless otherwise specified	Total	Common Stock	Paid-In Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	Noncontrolling Interest
Beginning Balance at Dec. 31, 2011	$ 919,217	$ 126,900	$ 179,052	$ 619,629	$ (7,494)	$ 1,130
Beginning Balance (in shares) at Dec. 31, 2011		63,449
Net income	109,003			109,003
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	109,003
Other comprehensive income	7,088				7,088
Dividends declared ($0.88 per share for 2012 and $0.96 per share for 2013, $1.00 per share for 2014)	(55,681)			(55,681)
Shares repurchased and retired (in shares)		(522)
Shares repurchased and retired	(15,000)	(1,043)		(13,957)
Share-based compensation expense, exercises and other (in shares)		344
Share-based compensation expense, exercises and other	9,029	687	8,342
Ending Balance at Dec. 31, 2012	973,656	126,544	187,394	658,994	(406)	1,130
Ending Balance (in shares) at Dec. 31, 2012		63,271
Net income	110,882			110,882
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	110,882
Other comprehensive income	9,974				9,974
Dividends declared ($0.88 per share for 2012 and $0.96 per share for 2013, $1.00 per share for 2014)	(60,573)			(60,573)
Shares repurchased and retired (in shares)	(560)	(560)
Shares repurchased and retired	(18,876)	(1,120)		(17,756)
Share-based compensation expense, exercises and other (in shares)		385
Share-based compensation expense, exercises and other	9,980	769	9,211
Ending Balance at Dec. 31, 2013	1,025,043	126,193	196,605	691,547	9,568	1,130
Ending Balance (in shares) at Dec. 31, 2013	63,096	63,096
Net income	66,503			66,503
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	66,503
Other comprehensive income	(33,569)				(33,569)
Dividends declared ($0.88 per share for 2012 and $0.96 per share for 2013, $1.00 per share for 2014)	(62,934)			(62,934)
Shares repurchased and retired (in shares)	(300)	(291)
Shares repurchased and retired	(9,934)	(583)		(9,351)
Share-based compensation expense, exercises and other (in shares)		265
Share-based compensation expense, exercises and other	7,554	530	7,024
Purchase of noncontrolling interest	(1,825)		(695)			(1,130)
Ending Balance at Dec. 31, 2014	$ 990,838	$ 126,140	$ 202,934	$ 685,765	$ (24,001)	$ 0
Ending Balance (in shares) at Dec. 31, 2014	63,070	63,070