Guaranteed Benefit Features (Account Balances Of Variable Annuity Contracts With Guarantees Invested In Separate Accounts) (Details) - Variable Annuity [Member] - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016
Account Balances Of Variable Annuity Contracts With Guarantees Invested In Separate Accounts [Line Items]
Total	$ 113,120	$ 109,182
Percent of total variable annuity separate account values	99.00%	99.00%
Domestic equity
Account Balances Of Variable Annuity Contracts With Guarantees Invested In Separate Accounts [Line Items]
Total	$ 54,433	$ 52,244
International equity
Account Balances Of Variable Annuity Contracts With Guarantees Invested In Separate Accounts [Line Items]
Total	18,131	17,396
Bonds
Account Balances Of Variable Annuity Contracts With Guarantees Invested In Separate Accounts [Line Items]
Total	27,564	27,532
Money Market
Account Balances Of Variable Annuity Contracts With Guarantees Invested In Separate Accounts [Line Items]
Total	$ 12,992	$ 12,010