Consolidated Statements of Changes in Equity - 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, 2014		63,070
Beginning Balance at Dec. 31, 2014	$ 990,838	$ 126,140	$ 202,934	$ 685,765	$ (24,001)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	43,166			43,166
Other comprehensive income (loss)	(20,787)				(20,787)
Dividends declared	(31,779)			(31,779)
Shares repurchased and retired (in shares)		(220)
Shares repurchased and retired	(7,440)	$ (440)		(7,000)
Share-based compensation expense, exercises and other (shares)		168
Share-based compensation expense, exercises and other	3,129	$ 336	2,793
Ending Balance (in shares) at Jun. 30, 2015		63,018
Ending Balance at Jun. 30, 2015	$ 977,127	$ 126,036	205,727	690,152	(44,788)
Beginning Balance (in shares) at Dec. 31, 2015	62,803	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	51,851			51,851
Other comprehensive income (loss)	1,562				1,562
Dividends declared	$ (31,914)			(31,914)
Shares repurchased and retired (in shares)	(600)	(575)
Shares repurchased and retired	$ (20,849)	$ (1,150)		(19,699)
Share-based compensation expense, exercises and other (shares)		282
Share-based compensation expense, exercises and other	$ 3,057	$ 565	2,492
Ending Balance (in shares) at Jun. 30, 2016	62,510	62,510
Ending Balance at Jun. 30, 2016	$ 996,297	$ 125,021	$ 214,435	$ 707,104	$ (50,263)