Investments (Narrative) (Details) - USD ($) $ in Millions	Sep. 30, 2015	Dec. 31, 2014
Investments [Abstract]
Reduction of net unrealized gains on investments included in AOCI due to shadow adjustments	$ 1,046	$ 1,288
Future capital call commitments for limited partnership investments	414
Mortgage loan commitments	29
Commitments to purchase or fund privately placed debt securities	81
Commitments to sell various privately placed debt securities	$ 43