Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands		3 Months Ended								12 Months Ended
		Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Earnings Per Share [Abstract]
Net earnings from continuing operations						$ 71,057	$ 62,276	$ 11,230	$ 25,905	$ 299,619	$ 170,468	$ 45,477
Undistributed Earnings (Loss) Allocated to Participating Securities, Basic	[1]									2,892	1,959	1,096
Net earnings from continuing operations allocated to common shares										296,727	168,509	44,381
Net loss from discontinued operations allocated to common shares										0	(1,545)	(348)
Net earnings allocated to common shares										$ 296,727	$ 166,964	$ 44,033
Weighted-average basic shares and unvested restricted stock outstanding										107,401	87,871	42,506
Less: weighted-average unvested restricted stock outstanding										(1,074)	(1,018)	(1,683)
Weighted-average basic shares outstanding										106,327	86,853	40,823
Net earnings from continuing operations						$ 0.69	$ 0.60	$ 0.11	$ 0.57	$ 2.79	$ 1.94	$ 1.09
Net loss from discontinued operations										0.00	(0.02)	(0.01)
Basic net income per share (usd per share)		$ 0.60	$ 0.68	$ 0.83	$ 0.71	0.69	0.60	0.10	0.55	$ 2.79	$ 1.92	$ 1.08
Net earnings allocated to common shares										296,727	166,964	44,033
Net earnings from continuing operations						0.69	0.60	0.11	0.57	$ 2.79	$ 1.94	$ 1.09
Net loss from discontinued operations										0.00	(0.02)	(0.01)
Diluted net income per share (usd per share)		$ 0.60	$ 0.68	$ 0.83	$ 0.71	$ 0.69	$ 0.60	$ 0.10	$ 0.55	$ 2.79	$ 1.92	$ 1.08

[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.