Earnings Per Share (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Earnings Per Share [Abstract]
Income (Loss) from Continuing Operations Attributable to Parent									$ 170,468		$ 45,477		$ 56,801
Less: earnings allocated to unvested restricted stock(1)									(1,959)	[1]	(1,096)	[1]	(1,845)	[1]
Net earnings from continuing operations allocated to common shares									168,509		44,381		54,956
Net (loss) earnings from discontinued operations allocated to common shares									(1,545)		(348)		0
Net earnings allocated to common shares									$ 166,964		$ 44,033		$ 54,956
Weighted-average basic shares and unvested restricted stock outstanding									87,871		42,506		37,370
Less: weighted-average unvested restricted stock outstanding									(1,018)		(1,683)		(1,685)
Weighted-average basic shares outstanding									86,853		40,823		35,685
Net earnings from continuing operations	$ 690.00	$ 600.00	$ 110.00	$ 570.00	$ 70	$ 530.00	$ 110.00	$ 370.00	$ 1.94		$ 1.09		$ 1.54
Net loss from discontinued operations									$ (0.02)		$ (0.01)		$ 0.00
Basic net income per share (usd per share)	$ 690.00	$ 600.00	$ 100.00	$ 550.00	$ 60	$ 530.00	$ 110.00	$ 370.00	$ 1.92		$ 1.08		$ 1.54
Net earnings allocated to common shares									166,964		44,033		54,956
Net earnings from continuing operations	$ 690.00	$ 600.00	$ 110.00	$ 570.00	$ 70	$ 530.00	$ 110.00	$ 370.00	$ 1.94		$ 1.09		$ 1.54
Net loss from discontinued operations									$ (0.02)		$ (0.01)		$ 0.00
Diluted net income per share (usd per share)	$ 690.00	$ 600.00	$ 100.00	$ 550.00	$ 60	$ 530.00	$ 110.00	$ 370.00	$ 1.92		$ 1.08		$ 1.54

[1] (1)Represents cash dividends paid to holders of unvested restricted stock, net of estimated forfeitures, plus undistributed earnings amounts available to holders of unvested restricted stock, if any.