Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended						6 Months Ended
	Jun. 30, 2019		Mar. 31, 2019		Jun. 30, 2018		Jun. 30, 2019	Jun. 30, 2018
Earnings Per Share [Abstract]
Net earnings from continuing operations	$ 128,125		$ 112,604		$ 115,735		$ 240,729	$ 234,011
Less: Earnings allocated to unvested restricted stock	(1,190)	[1]	(1,163)	[1]	(1,348)	[1]	(2,343)	(2,469)
Net earnings allocated to common shares	$ 126,935		$ 111,441		$ 114,387		$ 238,386	$ 231,542
Weighted-average basic shares and unvested restricted stock outstanding (shares)	120,042		122,227		126,082		121,128	126,780
Weighted-average unvested restricted stock outstanding (shares)	(1,462)		(1,352)		(1,466)		(1,407)	(1,439)
Weighted-average basic shares outstanding (shares)	118,580		120,875		124,616		119,721	125,341
Basic net income per share (usd per share)	$ 1.07		$ 0.92		$ 0.92		$ 1.99	$ 1.85
Net earnings from continuing operations allocated to common shares	$ 126,935		$ 111,441		$ 114,387		$ 238,386	$ 231,542
Diluted net income per share (usd per share)	$ 1.07		$ 0.92		$ 0.92		$ 1.99	$ 1.85

[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.