Quarterly Financial Data (Unaudited) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Unaudited Quarterly Financial Data [Line Items]
Revenues									$ 2,425,800	$ 2,744,965	$ 2,614,748
Operating income									856,086	1,009,238	921,644
Income (loss) from continuing operations									4,479,586	907,621	657,101
Discontinued operations, net									518	397	1,582
Net income									4,480,104	908,018	658,683
Net income available to Common Shares									$ 4,289,072	$ 863,277	$ 627,163
Earnings Per Share, Basic [Abstract]
Net income available to Common Shares									$ 11.75	$ 2.37	$ 1.74
Weighted average Common Shares outstanding									365,002	363,498	361,181
Earnings Per Share, Diluted [Abstract]
Net income available to Common Shares									$ 11.68	$ 2.36	$ 1.73
Weighted average Common Shares outstanding									381,992	380,620	377,735
Scenario, Previously Reported [Member]
Unaudited Quarterly Financial Data [Line Items]
Revenues	$ 605,489	$ 606,074	$ 595,154	$ 619,083	$ 703,193	$ 696,289	$ 679,112	$ 666,371
Operating income	224,070	209,373	206,018	216,625	287,058	257,594	246,255	218,331
Income (loss) from continuing operations	301,987	217,246	228,365	3,731,988	213,673	205,375	298,504	190,069
Discontinued operations, net	394	246	35	(157)	47	81	114	155
Net income	302,381	217,492	228,400	3,731,831	213,720	205,456	298,618	190,224
Net income available to Common Shares	$ 276,477	$ 207,543	$ 218,067	$ 3,586,985	$ 202,989	$ 195,859	$ 285,587	$ 178,842
Earnings Per Share, Basic [Abstract]
Net income available to Common Shares	$ 0.76	$ 0.57	$ 0.60	$ 9.84	$ 0.56	$ 0.54	$ 0.79	$ 0.49
Weighted average Common Shares outstanding	365,256	365,109	365,047	364,592	363,828	363,579	363,476	363,098
Earnings Per Share, Diluted [Abstract]
Net income available to Common Shares	$ 0.75	$ 0.56	$ 0.59	$ 9.76	$ 0.55	$ 0.53	$ 0.78	$ 0.49
Weighted average Common Shares outstanding	381,860	382,373	382,065	382,243	381,220	380,663	380,491	380,327
ERPOP [Member]
Unaudited Quarterly Financial Data [Line Items]
Revenues									$ 2,425,800	$ 2,744,965	$ 2,614,748
Operating income									856,086	1,009,238	921,644
Income (loss) from continuing operations									4,479,586	907,621	657,101
Discontinued operations, net									518	397	1,582
Net income									4,480,104	908,018	658,683
Net income available to Units									$ 4,460,583	$ 897,518	$ 651,994
Earnings Per Share, Basic [Abstract]
Net income available to Common Shares									$ 11.75	$ 2.37	$ 1.74
Weighted average Units outstanding									378,829	377,074	374,899
Earnings Per Share, Diluted [Abstract]
Net income available to Common Shares									$ 11.68	$ 2.36	$ 1.73
Weighted average Common Shares outstanding									381,992	380,620	377,735
ERPOP [Member] | Scenario, Previously Reported [Member]
Unaudited Quarterly Financial Data [Line Items]
Revenues	$ 605,489	$ 606,074	$ 595,154	$ 619,083	$ 703,193	$ 696,289	$ 679,112	$ 666,371
Operating income	224,070	209,373	206,018	216,625	287,058	257,594	246,255	218,331
Income (loss) from continuing operations	301,987	217,246	228,365	3,731,988	213,673	205,375	298,504	190,069
Discontinued operations, net	394	246	35	(157)	47	81	114	155
Net income	302,381	217,492	228,400	3,731,831	213,720	205,456	298,618	190,224
Net income available to Units	$ 287,546	$ 215,896	$ 226,847	$ 3,730,294	$ 211,039	$ 203,637	$ 296,941	$ 185,901
Earnings Per Share, Basic [Abstract]
Net income available to Common Shares	$ 0.76	$ 0.57	$ 0.60	$ 9.84	$ 0.56	$ 0.54	$ 0.79	$ 0.49
Weighted average Units outstanding	379,081	379,008	378,934	378,289	377,380	377,147	377,063	376,696
Earnings Per Share, Diluted [Abstract]
Net income available to Common Shares	$ 0.75	$ 0.56	$ 0.59	$ 9.76	$ 0.55	$ 0.53	$ 0.78	$ 0.49
Weighted average Units outstanding	381,860	382,373	382,065	382,243	381,220	380,663	380,491	380,327