Consolidated Statement of Changes in Equity (Unaudited) (USD $) In Millions, except Share data	Total	General Partner [Member]	Limited Partner [Member]	Treasury Stock [Member]	Parent [Member]	Noncontrolling Interest [Member]
Equity at Dec. 31, 2011	$ 7,833	$ (271)	$ 4,038	$ (12)	$ 3,755	$ 4,078
Treasury units at Dec. 31, 2011	1,137,200			1,137,200
Net income	101	1	48	0	49	52
Other comprehensive income, net of tax	107	1	79	0	80	27
Cancellation of treasury units				(1,137,200)
Cancellation of treasury units, at cost	0	0	(12)	12	0	0
Partnership contributions	510	10	500	0	510	0
Partnership distributions	(10)	0	(10)	0	(10)	0
Investment segment distributions	(17)	0	0	0	0	(17)
Change in subsidiary equity and other	1	0	2	0	2	(1)
Equity at Mar. 31, 2012	$ 8,525	$ (259)	$ 4,645	$ 0	$ 4,386	$ 4,139
Treasury units at Mar. 31, 2012	0			0