Expenses Associated With Long-Duration Insurance Products - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		12 Months Ended
	Dec. 31, 2012	Dec. 31, 2010	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Long Duration Insurance Products [Line Items]
Percent of consolidated premiums and services revenues related to long-duration insurance products			2.00%
Future policy benefits payable	$ 1,858		$ 1,858	$ 1,663
Benefit expense with future policy benefits payable			136	114	266
Charge related to closed block of long-term care policies	29	139	29		139
Amortization of deferred acquisition costs			44	34	198
Write-down of deferred acquisition costs					147
Adjustment to future policy benefits assuming unrealized gains on investments realized and reinvested at current yields			119	47
Increase in future policy benefits payable		170			170
Increase in reinsurance recoverable		31			31
Deferred acquisition costs associated with our individual major medical policies	62		62	54
100% Coinsurance Agreements
Long Duration Insurance Products [Line Items]
Future policy benefits payable	220		220	224
Percentage of coinsurance agreement			100.00%	100.00%
Closed Block Long Term Care Policies
Long Duration Insurance Products [Line Items]
Future policy benefits payable	1,100		1,100	938
Individual Major Medical Policies
Long Duration Insurance Products [Line Items]
Future policy benefits payable	$ 282		$ 282	$ 233