Equity (Cash Distributions) (Details) - USD ($) $ / shares in Units, $ in Millions			3 Months Ended								12 Months Ended
		Jan. 23, 2020	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
Incentive Distribution Made to Managing Member or General Partner [Line Items]
Distributions to preferred units											$ 2,758	$ 2,060	$ 1,288
Subsequent Event
Incentive Distribution Made to Managing Member or General Partner [Line Items]
Distribution made to limited partner, declaration date		Jan. 23, 2020
Distributions to preferred units		$ 715
Cash distributions declared per limited partner common unit		$ 0.6875
Distribution made to limited partner, distribution date		Feb. 14, 2020
Distribution made to limited partner, date of record		Feb. 04, 2020
Limited Partners Common Units
Incentive Distribution Made to Managing Member or General Partner [Line Items]
Distributions to preferred units	[1]										$ 2,635	$ 1,985	$ 895
Cash distributions declared per limited partner common unit			$ 0.6875	$ 0.6775	$ 0.6675	$ 0.6575	$ 0.6475	$ 0.6375	$ 0.6275	$ 0.6175	$ 2.6900	$ 2.5300

[1] See Note 8 for distribution information.