CONDENSED CONSOLIDATED STATEMENTS OF CHANGES IN PARTNERS' CAPITAL - USD ($) $ in Millions	Total	Noncontrolling Interests	Class A Shares	Limited Partners Class A Shares
Balance, beginning of period at Dec. 31, 2015	$ 9,234	$ 7,472		$ 1,762
Increase (Decrease) in Partners' Capital
Net income	538	436		102
Cash distributions to partners	(1,291)	(1,112)		(179)
Deferred tax asset (Note 9)	102			102
Sales of common units by a subsidiary (Note 9)	283	283
Change in ownership interest in connection with Exchange Right exercises		17		(17)
Sale of Series A preferred units by a subsidiary	1,509	1,509
Other comprehensive income	0
Other	(1)	1		(2)
Balance, end of period at Sep. 30, 2016	10,374	8,606		1,768
Balance, beginning of period at Dec. 31, 2016	10,707	8,970		1,737
Increase (Decrease) in Partners' Capital
Net income	607	538		69
Cash distributions to partners	(1,170)	(945)		(225)
Deferred tax asset (Note 9)	390			390
Sales of Class A shares (Note 9)	1,535	1,073	$ 1,535	462
Sales of common units by a subsidiary (Note 9)	129	116		13
Issuance of common units by a subsidiary for acquisition of interest in Advantage Joint Venture (Note 6)	40	35		5
Other comprehensive income	256	204		52
Other	11	(14)		25
Balance, end of period at Sep. 30, 2017	$ 12,505	$ 9,977		$ 2,528