Consolidated Statements of Changes in Partnership Capital Subject to Mandatory Redemption - USD ($) $ in Millions	Total	Limited Partnership Capital [Member]	Subordinated Limited Partnership Capital [Member]	General Partnership Capital [Member]
TOTAL PARTNERSHIP CAPITAL SUBJECT TO MANDATORY REDEMPTION, at Dec. 31, 2012	$ 1,983	$ 696	$ 302	$ 985
Reserve for anticipated withdrawals at Dec. 31, 2012	(171)	(45)	(19)	(107)
Partnership capital subject to mandatory redemption, net of reserve for anticipated withdrawals at Dec. 31, 2012	1,812	651	283	878
Partnership loans outstanding at beginning of year at Dec. 31, 2012	170	0	0	170
Total partnership capital, including capital financed with partnership loans, net of reserve for anticipated withdrawals at Dec. 31, 2012	1,982	651	283	1,048
Issuance of partnership interests	135	0	32	103
Redemption of partnership interests	(115)	(10)	(10)	(95)
Income allocated to partners	674	78	73	523
Distributions	(380)	(31)	(49)	(300)
TOTAL PARTNERSHIP CAPITAL SUBJECT TO MANDATORY REDEMPTION at Dec. 31, 2013	2,081	688	329	1,064
Reserve for anticipated withdrawals at Dec. 31, 2013	(223)	(48)	(24)	(151)
Partnership capital subject to mandatory redemption, net of reserve for anticipated withdrawals at Dec. 31, 2013	1,858	640	305	913
Partnership loans outstanding at end of year at Dec. 31, 2013	215	0	0	215
Total partnership capital, including capital financed with partnership loans, net of reserve for anticipated withdrawals at Dec. 31, 2013	2,073	640	305	1,128
Total partnership capital, including capital financed with partnership loans at Dec. 31, 2013	2,296	688	329	1,279
Partnership loans outstanding, reduction to arrive at Partnership Capital	(215)	0	0	(215)
Issuance of partnership interests	141	0	47	94
Redemption of partnership interests	(125)	(8)	(16)	(101)
Income allocated to partners	770	82	87	601
Distributions	(443)	(30)	(60)	(353)
TOTAL PARTNERSHIP CAPITAL SUBJECT TO MANDATORY REDEMPTION at Dec. 31, 2014	2,218	684	362	1,172
Reserve for anticipated withdrawals at Dec. 31, 2014	(245)	(52)	(27)	(166)
Partnership capital subject to mandatory redemption, net of reserve for anticipated withdrawals at Dec. 31, 2014	1,973	632	335	1,006
Partnership loans outstanding at end of year at Dec. 31, 2014	198	0	1	197
Total partnership capital, including capital financed with partnership loans, net of reserve for anticipated withdrawals at Dec. 31, 2014	2,171	632	336	1,203
Total partnership capital, including capital financed with partnership loans at Dec. 31, 2014	2,416	684	363	1,369
Partnership loans outstanding, reduction to arrive at Partnership Capital	(198)	0	(1)	(197)
Issuance of partnership interests	471	296	43	132
Redemption of partnership interests	(161)	(12)	(9)	(140)
Income allocated to partners	838	121	93	624
Distributions	(491)	(47)	(67)	(377)
TOTAL PARTNERSHIP CAPITAL SUBJECT TO MANDATORY REDEMPTION at Dec. 31, 2015	2,610	990	394	1,226
Reserve for anticipated withdrawals at Dec. 31, 2015	(262)	(74)	(26)	(162)
Partnership capital subject to mandatory redemption, net of reserve for anticipated withdrawals at Dec. 31, 2015	2,348	916	368	1,064
Partnership loans outstanding at end of year at Dec. 31, 2015	218
Total partnership capital, including capital financed with partnership loans at Dec. 31, 2015	2,828	$ 990	396	1,442
Partnership loans outstanding, reduction to arrive at Partnership Capital	$ (218)		$ (2)	$ (216)