Investments (Details 28) (USD $) In Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2011	Dec. 31, 2010
Assets on deposit:
Regulatory agencies	$ 2,050	$ 2,110
Assets held in trust:
Collateral financing arrangements	5,342	5,340
Reinsurance arrangements	4885	3090
Assets pledged as collateral:
Invested assets pledged as collateral	7,700	7,800
Invested assets pledged as collateral	467	465
Total invested assets on deposit, held in trust and pledged as collateral	41,710	40,010
Federal Home Loan Bank of New York [Member]
Assets pledged as collateral:
Invested assets pledged as collateral	21,385	21,975
Federal Home Loan Bank of Boston [Member]
Assets pledged as collateral:
Invested assets pledged as collateral	529	211
Federal Home Loan Bank of Des Moines [Member]
Assets pledged as collateral:
Invested assets pledged as collateral	904	0
Funding agreements - Federal Agricultural Mortgage Corporation [Member]
Assets pledged as collateral:
Invested assets pledged as collateral	3,160	3,159
Federal Reserve Bank of New York [Member]
Assets pledged as collateral:
Invested assets pledged as collateral	1,686	1,822
Collateral financing arrangements [Member]
Assets pledged as collateral:
Invested assets pledged as collateral	273	112
Derivative transactions [Member]
Assets pledged as collateral:
Invested assets pledged as collateral	1,029	1,726
Short sale agreements [Member]
Assets pledged as collateral:
Invested assets pledged as collateral	$ 467	$ 465