Earnings Per Share (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Basic Net Earnings Per Common Shares [Abstract]
Earnings from continuing operations	$ 17,806	$ 17,686	$ 41,382	$ 43,652
Loss from discontinued operation	(8,240)	(389)	(9,451)	(1,138)
Net earnings available to common stockholders	9,566	17,297	31,931	42,514
Weighted average common shares outstanding (in shares)	22,884,939	22,999,832	22,901,832	22,945,424
Earnings from continuing operations per common share (in dollars per share)	$ 0.78	$ 0.77	$ 1.81	$ 1.90
Loss from discontinued operations per common share (in dollars per share)	$ (0.36)	$ (0.02)	$ (0.42)	$ (0.05)
Net earnings per common share - Basic (in dollars per share)	$ 0.42	$ 0.75	$ 1.39	$ 1.85
Diluted Net Earnings Per Common Share [Abstract]
Earnings from continuing operations	17,806	17,686	41,382	43,652
Loss from discontinued operation	(8,240)	(389)	(9,451)	(1,138)
Net earnings available to common stockholders	$ 9,566	$ 17,297	$ 31,931	$ 42,514
Plus incremental shares from assumed conversions [Abstract]
Dilutive effect of restricted and performance-based shares (in shares)	280,000	232,000	273,000	226,000
Dilutive effect of stock options (in shares)	4,000	7,000	6,000	8,000
Weighted average common shares outstanding - Diluted (in shares)	23,169,173	23,239,009	23,180,842	23,179,187
Earnings from continuing operations per common share (in dollars per share)	$ 0.77	$ 0.76	$ 1.79	$ 1.88
Loss from discontinued operations per common share (in dollars per share)	$ (0.36)	$ (0.02)	$ (0.41)	$ (0.05)
Net earnings per common share - Diluted (in dollars per share)	$ 0.41	$ 0.74	$ 1.38	$ 1.83
Stock Options [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)	6,000	11,000	4,000	9,000
Restricted and Performance-based Shares [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)	286,000	217,000	298,000	231,000