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	177	141		36
Cash distributions to partners	(430)	(375)		(55)
Deferred tax asset (Note 9)	94			94
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	118	117		1
Other	3	3
Balance, end of period at Mar. 31, 2016	10,705	8,884		1,821
Balance, beginning of period at Dec. 31, 2016	10,707	8,970		1,737
Increase (Decrease) in Partners' Capital
Net income	402	361		41
Cash distributions to partners	(372)	(315)		(57)
Deferred tax asset (Note 9)	386			386
Sales of Class A shares (Note 9)	1,535	1,073	$ 1,535	462
Partners Capital Account Public Sale Of Units By Subsidiary	129	116		13
Other comprehensive income	36	31		5
Other	4	(13)		17
Balance, end of period at Mar. 31, 2017	$ 12,827	$ 10,223		$ 2,604