Earnings Per Common Share Computations (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Earnings from continuing operations	$ 55,033	$ 58,152	$ 60,795
Earnings from continuing operations allocated to participating securities	(873)	(518)	(1,103)
Numerator for basic earnings from continuing operations per common share	54,160	57,634	59,692
Net earnings	54,900	58,276	64,355
Net earnings allocated to participating securities	(870)	(519)	(1,180)
Numerator for basic net earnings per common share	$ 54,030	$ 57,757	$ 63,175
Earnings Per Share, Basic and Diluted [Abstract]
Basic	17,294	17,047	16,638
Plus dilutive effect of stock options (in shares)	248	233	118
Plus dilutive effect of participating securities (in shares)	396	195	369
Diluted (in shares)	17,938	17,475	17,125
Earnings Per Share, Basic [Abstract]
Earnings from continuing operations	$ 3.13	$ 3.38	$ 3.59
Discontinued operations	$ (0.01)	$ 0.01	$ 0.21
Net earnings (per basic share)	$ 3.12	$ 3.39	$ 3.80
Earnings Per Share, Diluted [Abstract]
Earnings from continuing operations	$ 3.07	$ 3.33	$ 3.55
Discontinued operations	$ (0.01)	$ 0.01	$ 0.21
Net earnings (per share, diluted)	$ 3.06	$ 3.34	$ 3.76
Number Of Shares Excluded From Computation Of Diluated Loss Per Common Share (in shares)			18