Guaranteed Benefit Features (Account Balances Of Variable Annuity Contracts With Guarantees Invested In Separate Accounts) (Details) (Variable Annuity [Member], USD $) In Millions, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Asset type
Total	$ 86,864	$ 81,670
Percent of total variable annuity separate account values	98.00%	98.00%
Domestic equity
Asset type
Total	40,750	37,899
International equity
Asset type
Total	15,633	14,850
Bonds
Asset type
Total	22,125	21,174
Money Market
Asset type
Total	$ 8,356	$ 7,747