Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2019		Jun. 30, 2019		Sep. 30, 2018		Sep. 30, 2019	Sep. 30, 2018
Earnings Per Share [Abstract]
Net earnings from continuing operations	$ 110,026		$ 128,125		$ 116,287		$ 350,755	$ 350,298
Less: Earnings allocated to unvested restricted stock	(1,369)	[1]	(1,190)	[1]	(1,428)	[1]	(3,725)	(3,899)
Net earnings allocated to common shares	$ 108,657		$ 126,935		$ 114,859		$ 347,030	$ 346,399
Weighted-average basic shares and unvested restricted stock outstanding (shares)	119,831		120,042		123,657		120,691	125,728
Weighted-average unvested restricted stock outstanding (shares)	(1,622)		(1,462)		(1,537)		(1,480)	(1,473)
Weighted-average basic shares outstanding (shares)	118,209		118,580		122,120		119,211	124,255
Basic net income per share (usd per share)	$ 0.92		$ 1.07		$ 0.94		$ 2.91	$ 2.79
Net earnings from continuing operations allocated to common shares	$ 108,657		$ 126,935		$ 114,859		$ 347,030	$ 346,399
Diluted net income per share (usd per share)	$ 0.92		$ 1.07		$ 0.94		$ 2.91	$ 2.79

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