Basis of Presentation and Principles of Consolidation (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Change to Two-Class Method [Line Items]
Income from continuing operations used in basic per share calculation		$ 36,462	$ 21,384	$ 31,491	$ 71,268
Income from continuing operations used in diluted per share calculation		$ 36,462	$ 21,392	$ 31,491	$ 71,309
Weighted average shares used in basic per share calculation (in shares)		17,220	18,798	17,775	20,792
Weighted average shares used in diluted per share calculation (in shares)	[1]	17,229	19,021	17,789	21,186
Basic earnings per common share from continuing operations (in usd per share)		$ 2.12	$ 1.14	$ 1.77	$ 3.43
Diluted earnings per common share from continuing operations (in usd per share)		$ 2.12	$ 1.12	$ 1.77	$ 3.37
As Reported Under the Treasury Stock Method
Change to Two-Class Method [Line Items]
Income from continuing operations used in basic per share calculation			$ 22,123		$ 73,562
Income from continuing operations used in diluted per share calculation			$ 22,123		$ 73,562
Weighted average shares used in basic per share calculation (in shares)			18,798		20,792
Weighted average shares used in diluted per share calculation (in shares)			19,147		21,372
Basic earnings per common share from continuing operations (in usd per share)			$ 1.18		$ 3.54
Diluted earnings per common share from continuing operations (in usd per share)			$ 1.16		$ 3.44
Amount Allocated to Participating Securities
Change to Two-Class Method [Line Items]
Income from continuing operations used in basic per share calculation			$ (739)		$ (2,294)
Income from continuing operations used in diluted per share calculation			$ (731)		$ (2,253)
Weighted average shares used in basic per share calculation (in shares)			0		0
Weighted average shares used in diluted per share calculation (in shares)			(126)		(186)
Basic earnings per common share from continuing operations (in usd per share)			$ (0.04)		$ (0.11)
Diluted earnings per common share from continuing operations (in usd per share)			$ (0.04)		$ (0.07)

[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.