Consolidated Statements of Changes in Equity (unaudited) - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Paid-In Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss)
Beginning Balance (in shares) at Dec. 31, 2015		62,803
Beginning Balance at Dec. 31, 2015	$ 992,590	$ 125,606	$ 211,943	$ 706,866	$ (51,825)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	24,135			24,135
Other comprehensive income (loss)	8,419				8,419
Dividends declared	(15,989)			(15,989)
Shares repurchased and retired (in shares)		(163)
Shares repurchased and retired	(5,630)	$ (325)		(5,305)
Share-based compensation expense, exercises and other (shares)		162
Share-based compensation expense, exercises and other	1,396	$ 323	1,073
Ending Balance (in shares) at Mar. 31, 2016		62,802
Ending Balance at Mar. 31, 2016	$ 1,004,921	$ 125,604	213,016	709,707	(43,406)
Beginning Balance (in shares) at Dec. 31, 2016	61,031	61,031
Beginning Balance at Dec. 31, 2016	$ 960,038	$ 122,062	219,955	685,504	(67,483)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	18,785			18,785
Other comprehensive income (loss)	5,838				5,838
Dividends declared	(15,698)			(15,698)
Share-based compensation expense, exercises and other (shares)		171
Share-based compensation expense, exercises and other	$ 994	$ 341	653
Ending Balance (in shares) at Mar. 31, 2017	61,202	61,202
Ending Balance at Mar. 31, 2017	$ 969,957	$ 122,403	$ 220,608	$ 688,591	$ (61,645)