Earnings Per Common Share Computations (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Earnings Per Share [Abstract]
Earnings from continuing operations	$ 9,158	$ 5,973	$ 60,515	$ 55,903
Participating Securities, Distributed and Undistributed Earnings	(193)	(78)	(1,279)	(729)
Numerator for basic earnings from continuing operations per common share	8,965	5,895	59,236	55,174
Net earnings	9,249	5,973	60,605	55,902
Net earnings allocated to participating securities	(195)	(78)	(1,281)	(729)
Numerator for basic net earnings per common share	9,054	5,895	59,324	55,173
Income Loss From Continuing Operations, Diluted	9,158	5,973	60,515	55,903
Net Income (Loss) Available to Common Stockholders, Diluted	$ 9,249	$ 5,973	$ 60,605	$ 55,902
Earnings Per Share, Basic and Diluted [Abstract]
Basic (in shares)	17,328	17,130	17,269	17,004
Plus dilutive effect of stock options (in shares)	254	220	239	236
Plus dilutive effect of participating securities (in shares)	373	225	373	225
Diluted (in shares)	17,955	17,575	17,881	17,465
Income (Loss) from Continuing Operations, Per Basic Share	$ 0.52	$ 0.34	$ 3.43	$ 3.24
Income (Loss) from Discontinued Operations and Disposal of Discontinued Operations, Net of Tax, Per Basic Share	$ 0.00	$ 0	$ 0.01	$ 0
Net earnings (in dollars per share), Basic	$ 0.52	$ 0.34	$ 3.44	$ 3.24
Net earnings (in dollars per share), Diluted	$ 0.52	$ 0.34	$ 3.39	$ 3.20
Income (Loss) from Continuing Operations, Per Diluted Share	$ 0.51	$ 0.34	$ 3.38	$ 3.20
Income (Loss) from Discontinued Operations and Disposal of Discontinued Operations, Net of Tax, Per Diluted Share	$ 0.01	$ 0	$ 0.01	$ 0