Derivatives and Hedging Activities (Details 4) (USD $) In Millions, unless otherwise specified			12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2012 2013	Dec. 31, 2012 2014	Dec. 31, 2012 2015	Dec. 31, 2012 2016	Dec. 31, 2012 2017	Dec. 31, 2012 2018-2027
Summary of Option Premiums Payable and Receivable
Premiums Payable			$ 373	$ 348	$ 320	$ 289	$ 238	$ 785
Premiums Receivable			57	55	54	46	41	104
Gross notional amount of index options and futures contracts	1,300	1,300
Gross notional amount of forwards, futures, total return swaps and commodity swaps	146	123
Gross notional amount of foreign currency forward contracts	14	26
Gross notional amount of total return swap to hedge equity price risk		$ 17