Certain Long-Duration Contracts With Guarantees (Separate Account Investment Options) (Details) - Annuity Contracts - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Fair Value, Separate Account Investment [Line Items]
Separate Account Investment Options	$ 158,206	$ 140,595
Equity funds
Fair Value, Separate Account Investment [Line Items]
Separate Account Investment Options	93,010	78,626
Bond funds
Fair Value, Separate Account Investment [Line Items]
Separate Account Investment Options	60,074	57,477
Balanced funds
Fair Value, Separate Account Investment [Line Items]
Separate Account Investment Options	1,592	1,370
Money market funds
Fair Value, Separate Account Investment [Line Items]
Separate Account Investment Options	$ 3,530	$ 3,122