Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Basic Net Earnings Per Common Shares [Abstract]
Earnings from continuing operations	$ 19,194	$ 17,806	$ 42,341	$ 41,382
Loss from discontinued operation	(728)	(8,240)	(1,549)	(9,451)
Net earnings available to common stockholders	$ 18,466	$ 9,566	$ 40,792	$ 31,931
Weighted average common shares outstanding (in shares)	22,770,865	22,884,939	22,865,978	22,901,832
Earnings from continuing operations per common share (in dollars per share)	$ 0.84	$ 0.78	$ 1.85	$ 1.81
Loss from discontinued operations per common share (in dollars per share)	(0.03)	(0.36)	(0.07)	(0.42)
Net earnings per common share - Basic (in dollars per share)	$ 0.81	$ 0.42	$ 1.78	$ 1.39
Diluted Net Earnings Per Common Share [Abstract]
Earnings from continuing operations	$ 19,194	$ 17,806	$ 42,341	$ 41,382
Loss from discontinued operation	(728)	(8,240)	(1,549)	(9,451)
Net earnings available to common stockholders	$ 18,466	$ 9,566	$ 40,792	$ 31,931
Plus incremental shares from assumed conversions [Abstract]
Dilutive effect of restricted stock and performance-based stock (in shares)	363,000	280,000	354,000	273,000
Dilutive effect of stock options (in shares)	0	4,000	0	6,000
Weighted average common shares outstanding - Diluted (in shares)	23,133,869	23,169,173	23,220,381	23,180,842
Earnings from continuing operations per common share (in dollars per share)	$ 0.83	$ 0.77	$ 1.82	$ 1.79
Loss from discontinued operations per common share (in dollars per share)	(0.03)	(0.36)	(0.06)	(0.41)
Net earnings per common share - Diluted (in dollars per share)	$ 0.80	$ 0.41	$ 1.76	$ 1.38
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)	0	6,000	0	4,000
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)	315,000	286,000	338,000	298,000