Consolidated Statements of Shareholders' Equity (USD $) In Thousands, except Share data, unless otherwise specified	Total	Common Stock	Accumulated Other Comprehensive Income (Loss) [Member]	Retained Earnings [Member]
Stockholders' Equity Attributable to Parent, Beginning of Period at Dec. 31, 2011	$ 584,030	$ 260,199	$ 0	$ 323,831
Shares, Outstanding, Beginning of Period at Dec. 31, 2011		17,178,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings and comprehensive income	58,276			58,276
Issuance of common stock for convertible note payable, shares		155,000
Issuance of common stock for convertible note payable, value	5,663	5,663
Issuance of common stock for employee benefit plans, shares		19,000
Issuance of common stock for employee benefit plan, value	714	714
Issuance of common stock for long-term incentive plan, shares		158,000
Issuance of common stock for long-term incentive plan, value	4,207	4,207
Tax windfall/(shortfall) provision from share-based compensation	1,407	1,407
Repurchase of common stock, shares		(84,000)
Stock repurchased during period, value	(5,094)	(5,094)
Stock Repurchased and Retired During Period, Value	0
Restricted stock forfeitures	0	(1,000)
Grant of restricted stock, shares		23,000
Amortization of restricted stock, value	6,377	6,377
Cash dividends	(12,351)			(12,351)
Restricted dividends	(170)			(170)
Stock option plan expense	1,236	1,236
Foreign currency translation adjustment, net of ($70) tax effect	0
Stockholders' Equity Attributable to Parent, End of Period at Dec. 31, 2012	644,295	274,709	0	369,586
Shares, Outstanding, End of Period at Dec. 31, 2012		17,448,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings and comprehensive income	54,900			54,900
Issuance of common stock, stock option exercises, shares		7,000
Issuance of common stock, stock option exercises, value	330	330
Issuance of common stock for employee benefit plans, shares		17,000
Issuance of common stock for employee benefit plan, value	805	805
Issuance of common stock for long-term incentive plan, shares		174,000
Issuance of common stock for long-term incentive plan, value	6,371	6,371
Tax windfall/(shortfall) provision from share-based compensation	2,981	2,981
Repurchase of common stock, shares		(133,000)
Stock repurchased during period, value	(10,723)	(10,723)
Stock Repurchased and Retired During Period, Value	0
Restricted stock forfeitures		(1,000)
Grant of restricted stock, shares		436,000
Amortization of restricted stock, value	20,525	20,525
Cash dividends	(15,186)			(15,186)
Restricted dividends	(466)			(466)
Stock option plan expense	957	957
Foreign currency translation adjustment, net of ($70) tax effect	0
Stockholders' Equity Attributable to Parent, End of Period at Dec. 31, 2013	704,789	295,955	0	408,834
Shares, Outstanding, End of Period at Dec. 31, 2013		17,948,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings and comprehensive income	46,357			46,357
Issuance of common stock, stock option exercises, shares		186,000
Issuance of common stock, stock option exercises, value	6,417	6,417
Issuance of common stock for employee benefit plans, shares		15,000
Issuance of common stock for employee benefit plan, value	1,058	1,058
Tax windfall/(shortfall) provision from share-based compensation	7,708	7,708
Repurchase of common stock, shares	(691,000)	(160,000)
Stock repurchased during period, value	(15,021)	(15,021)
Stock Repurchased and Retired During Period, Shares	(691,000)
Stock Repurchased and Retired During Period, Value	(61,561)
Restricted stock forfeitures		(9,000)
Grant of restricted stock, shares		26,000
Amortization of restricted stock, value	11,527	11,527
Cash dividends	(17,026)			(17,026)
Restricted dividends	(319)			(319)
Stock option plan expense	404	404
Stock Issued During Period, Shares, Acquisitions	157,000
Stock Issued During Period, Value, Acquisitions	15,793
Foreign currency translation adjustment, net of ($70) tax effect	(125)		(125)
Stockholders' Equity Attributable to Parent, End of Period at Dec. 31, 2014	$ 700,001	$ 262,280	$ (125)	$ 437,846
Shares, Outstanding, End of Period at Dec. 31, 2014		17,472,000