Earnings Per Share (Details 1) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands		3 Months Ended			6 Months Ended
		Jun. 30, 2015	Mar. 31, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Earnings Per Share [Abstract]
Net earnings from continuing operations		$ 85,083	$ 73,079	$ 11,230	$ 158,162	$ 37,135
Less: Earnings allocated to unvested restricted stock	[1]	(807)	(819)	(290)	(1,570)	(424)
Net earnings from continuing operations allocated to common shares		84,276	72,260	10,940	156,592	36,711
Net (loss) earnings from discontinued operations allocated to common shares		0	0	(675)	0	(1,500)
Net earnings allocated to common shares		$ 84,276	$ 72,260	$ 10,265	$ 156,592	$ 35,211
Weighted-average basic shares and unvested restricted stock outstanding (shares)		103,030	103,035	98,817	103,033	72,454
Weighted-average unvested restricted stock outstanding (shares)		(1,060)	(1,122)	(678)	(1,091)	(911)
Weighted-average basic shares outstanding (shares)		101,970	101,913	98,139	101,942	71,543
Net earnings from continuing operations (usd per share)		$ 0.83	$ 0.71	$ 0.11	$ 1.54	$ 0.51
Net loss from discontinued operations (usd per share)		0.00	0.00	(0.01)	0.00	(0.02)
Basic net income per share (usd per share)		$ 0.83	$ 0.71	$ 0.10	$ 1.54	$ 0.49
Net earnings allocated to common shares (shares)		84,276	72,260	10,265	156,592	35,211
Net earnings from continuing operations (usd per share)		$ 0.83	$ 0.71	$ 0.11	$ 1.54	$ 0.51
Net loss from discontinued operations (usd per share)		0.00	0.00	(0.01)	0.00	(0.02)
Diluted net income per share (usd per share)		$ 0.83	$ 0.71	$ 0.10	$ 1.54	$ 0.49

[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.