Net Income Per Limited Partner Unit (Schedule of Net Income By Class of Participating Securities) (Details) - USD ($) $ / shares in Units, $ in Millions	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
Partners' Capital [Abstract]
Distributions declared									$ 785	$ 655	$ 458
Distributions less than net income attributable to the Partnership									138	141	3
Net income attributable to the Partnership	$ 255	$ 237	$ 233	$ 198	$ 221	$ 217	$ 186	$ 172	$ 923	796	461
Net income attributable to the Partnership per limited partner unit—basic (in usd per share)	$ 1.08	$ 1.18	$ 1.23	$ 0.96	$ 1.16	$ 1.17	$ 0.99	$ 0.91
Net income attributable to the Partnership per limited partner unit—diluted (in usd per share)	$ 1.06	$ 1.15	$ 1.15	$ 0.92	$ 1.09	$ 1.10	$ 0.94	$ 0.87
Common Units
Partners' Capital [Abstract]
Net income attributable to the Partnership (diluted)										$ 547	$ 299
Weighted-average units outstanding—basic (in shares)									167,655,306	122,768,582	112,044,824
Dilutive effect of preferred units (in shares)									13,819,791	13,819,791	3,294,032
Weighted-average units outstanding—diluted (in shares)									181,475,097	136,588,373	115,338,856
Net income attributable to the Partnership per limited partner unit—basic (in usd per share)									$ 4.45	$ 4.22	$ 2.60
Net income attributable to the Partnership per limited partner unit—diluted (in usd per share)									$ 4.29	$ 4.00	$ 2.59
Limited Partner
Partners' Capital [Abstract]
Dilutive effect of preferred units										$ 28	$ 7
Limited Partner | Common Units
Partners' Capital [Abstract]
Distributions declared									$ 609	382	291
Distributions less than net income attributable to the Partnership									137	137	1
Net income attributable to the Partnership									746	519	292
Dilutive effect of preferred units									32
Net income attributable to the Partnership (diluted)									778
Limited Partner | Preferred Unitholders Public
Partners' Capital [Abstract]
Distributions declared									37	37	9
Distributions less than net income attributable to the Partnership									0	0	0
Net income attributable to the Partnership									37	37	9
General Partner
Partners' Capital [Abstract]
Distributions declared									139	236	158
Distributions less than net income attributable to the Partnership									1	4	2
Net income attributable to the Partnership									$ 140	$ 240	$ 160