Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands		3 Months Ended
		Mar. 31, 2019	Dec. 31, 2018	Mar. 31, 2018
Earnings Per Share [Abstract]
Net earnings from continuing operations		$ 112,604	$ 115,041	$ 118,276
Less: Earnings allocated to unvested restricted stock	[1]	(1,163)	(1,219)	(1,115)
Net earnings allocated to common shares		$ 111,441	$ 113,822	$ 117,161
Weighted-average basic shares and unvested restricted stock outstanding (shares)		122,227	123,238	127,487
Weighted-average unvested restricted stock outstanding (shares)		(1,352)	(1,426)	(1,413)
Weighted-average basic shares outstanding (shares)		120,875	121,812	126,074
Basic net income per share (usd per share)		$ 0.92	$ 0.93	$ 0.93
Net earnings from continuing operations allocated to common shares		$ 111,441	$ 113,822	$ 117,161
Diluted net income per share (usd per share)		$ 0.92	$ 0.93	$ 0.93

[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.