Consolidated Statement of Shareholders' Equity (USD $) In Thousands, except Share data, unless otherwise specified	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Treasury Stock [Member]
Stockholders' Equity Attributable to Parent period start at Dec. 31, 2011	$ 373,071	$ 26,496	$ 109,584	$ 361,389	$ (117,946)	$ (6,452)
Treasury Stock, Shares, Outstanding period start at Dec. 31, 2011						258,424
Common Stock, Shares, Outstanding period start at Dec. 31, 2011		26,495,828
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings	55,025			55,025
Other Comprehensive Income (Loss), Net of Tax	(3,644)				(3,644)
Dividends	(16,941)			(16,941)
Purchase of treasury shares						21,343
Purchase of treasury shares value	(733)					(733)
Stock awards shares issued, net of tax expense of		291,037
Stock awards value issued, net of tax expense of $834, $543, and $883, respectively	7,550	291	7,160
Shares Repurchased, Net of Shares Issued, in Connection With Stock Awards, Shares						(9,571)
Shares Repurchased, Net of Shares Issued, in Connection With Stock Awards, Value						99
Share-based compensation expense, shares		94,392
Share-based compensation expense, value	5,865	94	5,778
Shares Repurchased, Net of Shares Issued, in Connection With Share-Based Compensation, Shares						7,277
Shares Repurchased, Net of Shares Issued, in Connection With Share-Based Compensation, Value						(7)
Stockholders' Equity Attributable to Parent period end at Dec. 31, 2012	420,193	26,881	122,522	399,473	(121,590)	(7,093)
Treasury Stock, Shares, Outstanding period end at Dec. 31, 2012						277,473
Common Stock, Shares, Outstanding period end at Dec. 31, 2012		26,881,257
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings	57,100			57,100
Other Comprehensive Income (Loss), Net of Tax	40,469				40,469
Dividends	(17,132)			(17,132)
Purchase of treasury shares						18,468
Purchase of treasury shares value	(644)					(644)
Stock awards shares issued, net of tax expense of		216,510
Stock awards value issued, net of tax expense of $834, $543, and $883, respectively	6,333	217	6,076
Shares Repurchased, Net of Shares Issued, in Connection With Stock Awards, Shares						(3,825)
Shares Repurchased, Net of Shares Issued, in Connection With Stock Awards, Value						40
Share-based compensation expense, shares		92,155
Share-based compensation expense, value	4,973	92	4,919
Shares Repurchased, Net of Shares Issued, in Connection With Share-Based Compensation, Shares						38,371
Shares Repurchased, Net of Shares Issued, in Connection With Share-Based Compensation, Value						(38)
Stockholders' Equity Attributable to Parent period end at Dec. 31, 2013	511,292	27,190	133,517	439,441	(81,121)	(7,735)
Treasury Stock, Shares, Outstanding period end at Dec. 31, 2013	330,487					330,487
Common Stock, Shares, Outstanding period end at Dec. 31, 2013		27,189,922
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings	57,872			57,872
Other Comprehensive Income (Loss), Net of Tax	(45,140)				(45,140)
Dividends	(17,329)			(17,329)
Purchase of treasury shares						21,312
Purchase of treasury shares value	(853)					(853)
Stock awards shares issued, net of tax expense of		235,233
Stock awards value issued, net of tax expense of $834, $543, and $883, respectively	6,412	235	6,992
Shares Repurchased, Net of Shares Issued, in Connection With Stock Awards, Shares						16,352
Shares Repurchased, Net of Shares Issued, in Connection With Stock Awards, Value						(815)
Share-based compensation expense, shares		93,071
Share-based compensation expense, value	5,411	93	5,336
Shares Repurchased, Net of Shares Issued, in Connection With Share-Based Compensation, Shares						17,791
Shares Repurchased, Net of Shares Issued, in Connection With Share-Based Compensation, Value						(18)
Stockholders' Equity Attributable to Parent period end at Dec. 31, 2014	$ 517,665	$ 27,518	$ 145,845	$ 479,984	$ (126,261)	$ (9,421)
Treasury Stock, Shares, Outstanding period end at Dec. 31, 2014	385,942					385,942
Common Stock, Shares, Outstanding period end at Dec. 31, 2014		27,518,226