Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands		3 Months Ended								12 Months Ended
		Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Earnings Per Share [Abstract]
Net earnings		$ 117,881	$ 110,026	$ 128,125	$ 112,604					$ 468,636	$ 465,339	$ 357,818
Participating Securities, Distributed and Undistributed Earnings (Loss), Basic	[1]									5,182	5,119
Net earnings from continuing operations						$ 115,041	$ 116,287	$ 115,735	$ 118,276	468,636	465,339
Undistributed Earnings (Loss) Allocated to Participating Securities, Basic	[1]											(4,184)
Net Income (Loss) Available to Common Stockholders, Basic										463,454	460,220
Net earnings allocated to common shares										$ 463,454	$ 460,220	$ 353,634
Weighted-average basic shares and unvested restricted stock outstanding										120,468	125,100	123,060
Less: weighted-average unvested restricted stock outstanding										(1,502)	(1,460)	(1,447)
Weighted-average basic shares outstanding										118,966	123,640	121,613
Earnings Per Share, Basic (usd per share)										$ 3.90	$ 3.72	$ 2.91
Diluted income per share (usd per share)		$ 0.98	$ 0.92	$ 1.07	$ 0.92	$ 0.93	$ 0.94	$ 0.92	$ 0.93	$ 3.90	$ 3.72	$ 2.91

[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.