Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016
Securities held to maturity, fixed maturities, fair value	$ 40,923	$ 40,021
Common stock, par value (in dollars per share)	$ 0.1	$ 0.1
Common stock, shares authorized (in shares)	1,900,000,000	1,900,000,000
Common stock, shares issued (in shares)	671,683,000	671,249,000
Asset derivatives	$ 580	$ 1,207
Liability derivatives	1,099	1,998
Investments Other Than Consolidated Variable Interest Entities
Securities available for sale, fixed maturities, amortized cost	66,118	62,195
Securities available for sale, perpetual securities, amortized cost	1,317	1,269
Securities available for sale, equity securities, cost	239	231
Securities held to maturity, fixed maturities, fair value	40,923	40,021
Variable Interest Entity, Consolidated
Securities available for sale, fixed maturities, amortized cost	4,143	4,168
Securities available for sale, perpetual securities, amortized cost	246	237
Securities available for sale, equity securities, cost	1,013	972
Asset derivatives	146	127
Liability derivatives	125	146
Commercial mortgage and middle market loans | Variable Interest Entity, Consolidated
Other investments held in unit trust, net of reserves, amortized cost	$ 926	$ 819