Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands		3 Months Ended
		Mar. 31, 2016	Mar. 31, 2015
Earnings Per Share [Abstract]
Income from continuing operations		$ 38,451	$ 42,155
Loss from discontinued operations, net of tax		0	(6,556)
Net income		38,451	35,599
Dividends and undistributed income allocated to participating shares		(1,465)	(1,380)
Income from continuing operations to common shares - basic		36,986	40,775
Effect of reallocating undistributed income from continuing operations to participating shares		2	1
Income from continuing operations to common shares - diluted		$ 36,988	$ 40,776
Weighted average common shares - basic (in shares)		16,094	18,269
Dilutive effect of share-based payment awards (in shares)		42	17
Weighted average common shares - diluted (in shares)	[1]	16,136	18,286
Basic earnings (loss) per common share:
Continuing operations (in usd per share)		$ 2.30	$ 2.23
Discontinued operations (in usd per share)		0.00	(0.36)
Basic earnings per common share (in usd per share)		2.30	1.87
Diluted earnings (loss) per common share:
Continuing operations (in usd per share)		2.29	2.23
Discontinued operations (in usd per share)		0.00	(0.36)
Diluted earnings per common share (in usd per share)		$ 2.29	$ 1.87
Stock options and share-based awards not included in diluted EPS calculation because their effect would have be antidilutive (in shares)		328	3

[1] Participating securities were included in the calculation of diluted earnings per share using the two-class method, as this calculation was more dilutive than the calculation using the treasury stock method.