Consolidated Balance Sheets (Parenthetical) - USD ($) shares in Thousands, $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Securities held to maturity, fixed maturities, fair value	$ 40,021	$ 37,520
Common stock, par value (in dollars per share)	$ 0.10	$ 0.10
Common stock, shares authorized (in shares)	1,900,000	1,900,000
Common stock, shares issued (in shares)	671,249	669,723
Asset derivatives	$ 1,207	$ 676
Liability derivatives	1,998	371
Investments Other Than Consolidated Variable Interest Entities
Securities available for sale, fixed maturities, amortized cost	62,195	56,903
Securities available for sale, perpetual securities, amortized cost	1,269	1,586
Securities available for sale, equity securities, cost	231	117
Securities held to maturity, fixed maturities, fair value	40,021	37,520
Variable Interest Entity, Consolidated
Securities available for sale, fixed maturities, amortized cost	4,168	3,739
Securities available for sale, perpetual securities, amortized cost	237	255
Securities available for sale, equity securities, cost	972	363
Asset derivatives	127	102
Liability derivatives	146	$ 293
Commercial mortgage and middle market loans [Member] | Variable Interest Entity, Consolidated
Other investments held in unit trust, net of reserves, amortized cost	$ 819