Quarterly Financial Data (Unaudited) (Details) - USD ($) $ / shares in Units, $ 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
Unaudited Quarterly Financial Data [Line Items]
Total revenues									$ 2,701,075	$ 2,578,434	$ 2,471,406
Operating income									1,356,544	1,115,370	1,004,528
Net income									1,009,708	685,192	628,381
Net income available to Common Shares									$ 967,287	$ 654,445	$ 600,363
Earnings per share:
Net income per share – basic									$ 2.61	$ 1.78	$ 1.64
Net income per share – diluted									$ 2.60	$ 1.77	$ 1.63
ERPOP [Member]
Unaudited Quarterly Financial Data [Line Items]
Total revenues									$ 2,701,075	$ 2,578,434	$ 2,471,406
Operating income									1,356,544	1,115,370	1,004,528
Net income									1,009,708	685,192	628,381
Net income available to Units									$ 1,003,321	$ 679,384	$ 622,967
Earnings per share:
Net income per share – basic									$ 2.61	$ 1.78	$ 1.64
Net income per share – diluted									$ 2.60	$ 1.77	$ 1.63
Scenario, Previously Reported [Member]
Unaudited Quarterly Financial Data [Line Items]
Total revenues	$ 683,919	$ 685,145	$ 669,517	$ 662,494	$ 652,743	$ 652,867	$ 639,808	$ 633,016
Operating income	408,952	368,363	369,260	209,969	219,282	339,403	217,603	339,082
Net income	301,306	277,846	321,299	109,257	122,388	223,846	118,410	220,548
Net income available to Common Shares	$ 288,992	$ 266,333	$ 308,196	$ 103,766	$ 116,415	$ 214,164	$ 112,830	$ 211,036
Earnings per share:
Net income per share – basic	$ 0.78	$ 0.72	$ 0.83	$ 0.28	$ 0.32	$ 0.58	$ 0.31	$ 0.57
Net income per share – diluted	$ 0.77	$ 0.71	$ 0.83	$ 0.28	$ 0.31	$ 0.58	$ 0.31	$ 0.57
Scenario, Previously Reported [Member] | ERPOP [Member]
Unaudited Quarterly Financial Data [Line Items]
Total revenues	$ 683,919	$ 685,145	$ 669,517	$ 662,494	$ 652,743	$ 652,867	$ 639,808	$ 633,016
Operating income	408,952	368,363	369,260	209,969	219,282	339,403	217,603	339,082
Net income	301,306	277,846	321,299	109,257	122,388	223,846	118,410	220,548
Net income available to Units	$ 299,687	$ 276,243	$ 319,706	$ 107,685	$ 120,837	$ 222,323	$ 117,129	$ 219,095
Earnings per share:
Net income per share – basic	$ 0.78	$ 0.72	$ 0.83	$ 0.28	$ 0.32	$ 0.58	$ 0.31	$ 0.57
Net income per share – diluted	$ 0.77	$ 0.71	$ 0.83	$ 0.28	$ 0.31	$ 0.58	$ 0.31	$ 0.57