Consolidated Statements Of Changes In Stockholders’ Equity - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Loss	Treasury Stock
Balance Beginning at Dec. 31, 2012	$ 940,893	$ 858	$ 418,318	$ 786,453	$ (15,660)	$ (249,076)
Balance at Beginning (in shares) at Dec. 31, 2012		74,840,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	79,306			79,306
Other comprehensive income (loss)	(11,132)				(11,132)
Common dividends declared ($0.16, $0.31 and $0.36)	(12,019)			(12,019)
Common stock issued, net of issuance costs	0
Share-based compensation expense	5,903		5,903
Restricted stock activity	(1,538)		(9,814)			8,276
Restricted stock activity (in shares)		234,000
Treasury stock issued to benefit plans	29		(114)			143
Treasury stock issued to benefit plans (in shares)		(3,000)
Balance Ending at Dec. 31, 2013	1,001,442	$ 858	414,293	853,740	(26,792)	(240,657)
Balance Ending (in shares) at Dec. 31, 2013		75,071,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	69,306			69,306
Other comprehensive income (loss)	10,937				10,937
Common dividends declared ($0.16, $0.31 and $0.36)	(23,530)			(23,530)
Common stock issued, net of issuance costs	38,300	$ 24	38,276
Common stock issued, net of issuance costs (in shares)		2,441,000
Share-based compensation expense	5,926		5,926
Restricted stock activity	(1,975)		(8,560)			6,585
Restricted stock activity (in shares)		176,000
Treasury stock issued to benefit plans	369		(137)			506
Treasury stock issued to benefit plans (in shares)		7,000
Balance Ending at Dec. 31, 2014	$ 1,100,775	$ 882	449,798	899,516	(15,855)	(233,566)
Balance Ending (in shares) at Dec. 31, 2014	77,695,000	77,695,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	$ 82,064			82,064
Other comprehensive income (loss)	(12,534)				(12,534)
Common dividends declared ($0.16, $0.31 and $0.36)	(28,064)			(28,064)
Purchase of treasury stock	(120)					(120)
Purchase of treasury stock (in shares)		(7,000)
Common stock issued, net of issuance costs	0
Share-based compensation expense	7,242		7,242
Restricted stock activity	(3,296)		(10,236)			6,940
Restricted stock activity (in shares)		267,000
Treasury stock issued to benefit plans	201		(132)			333
Treasury stock issued to benefit plans (in shares)		(3,000)
Balance Ending at Dec. 31, 2015	$ 1,146,268	$ 882	$ 446,672	$ 953,516	$ (28,389)	$ (226,413)
Balance Ending (in shares) at Dec. 31, 2015	77,952,000	77,952,000