Earnings Per Share (Details 1) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands		3 Months Ended			9 Months Ended
		Sep. 30, 2016	Jun. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Earnings Per Share [Abstract]
Net earnings from continuing operations		$ 93,895	$ 82,168	$ 69,616	$ 266,519	$ 227,778
Less: Earnings allocated to unvested restricted stock	[1]	(1,048)	(863)	(649)	(2,983)	(2,213)
Net earnings allocated to common shares		$ 92,847	$ 81,305	$ 68,967	$ 263,536	$ 225,565
Weighted-average basic shares and unvested restricted stock outstanding (shares)		121,818	121,799	103,048	121,739	103,038
Weighted-average unvested restricted stock outstanding (shares)		(1,401)	(1,481)	(985)	(1,425)	(1,055)
Weighted-average basic shares outstanding (shares)		120,417	120,318	102,063	120,314	101,983
Basic net income per share (usd per share)		$ 0.77	$ 0.68	$ 0.68	$ 2.19	$ 2.21
Net earnings from continuing operations allocated to common shares		$ 92,847	$ 81,305	$ 68,967	$ 263,536	$ 225,565
Diluted net income per share (usd per share)		$ 0.77	$ 0.68	$ 0.68	$ 2.19	$ 2.21

[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.