Reconciliation of Level Three Assets (Detail) (Level 3 Assets, USD $) In Millions, unless otherwise specified	12 Months Ended														12 Months Ended
	Dec. 31, 2013 U.S. Equity	Dec. 31, 2012 U.S. Equity	Dec. 31, 2013 Global ex Emerging Markets Equity	Dec. 31, 2012 Global ex Emerging Markets Equity	Dec. 31, 2013 Absolute Return Hedge Funds	Dec. 31, 2012 Absolute Return Hedge Funds	Dec. 31, 2013 Equity Hedge Funds	Dec. 31, 2012 Equity Hedge Funds	Dec. 31, 2013 Private Equity	Dec. 31, 2012 Private Equity	Dec. 31, 2013 Private Real Assets	Dec. 31, 2012 Private Real Assets	Dec. 31, 2013 Public Real Assets	Dec. 31, 2011 Public Real Assets	Dec. 31, 2013 Fixed Income	Dec. 31, 2012 Fixed Income
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	$ 73	$ 66	$ 16		$ 110	$ 80	$ 61	$ 50	$ 51	$ 47	$ 24	$ 16	$ 9	$ 9	$ 65
Realized Gains/ (Losses)	(1)				2	2			3	1	2	1	(1)
Unrealized Gains/ (Losses)	23	12	6	1	16	7	11	2	5	5	4	1	1		(3)
Purchases	9			15	12	29	25	13	6	9	11	10				65
Sales	(8)	(5)			(10)	(8)	(16)	(4)	(14)	(10)	(8)	(4)	(9)
Net Transfers Into/(Out of) Level 3										(1)
Ending Balance	$ 96	$ 73	$ 22	$ 16	$ 130	$ 110	$ 81	$ 61	$ 51	$ 51	$ 33	$ 24		$ 9	$ 62	$ 65