Net Unrealized Gains and Losses on Available-for-Sale Investment Securities Reflected as Separate Component of Accumulated Other Comprehensive Income (Loss) (Detail) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Components of Net Unrealized Investment Gains Losses Included in Accumulated Other Comprehensive Income Loss [Line Items]
Adjustments to DAC, PVFP, sales inducements and benefit reserves		$ (952)	$ (3,451)	$ (1,611)
Income taxes, net		(190)	(583)	(711)
Net unrealized investment gains (losses) including noncontrolling interests		633	1,160	1,346
Less: net unrealized investment gains (losses) attributable to noncontrolling interests		38	75	84
Net unrealized investment gains (losses)		595	1,085	1,262	$ 1,254
Net Unrealized Gains (Losses) On Investment Securities
Components of Net Unrealized Investment Gains Losses Included in Accumulated Other Comprehensive Income Loss [Line Items]
Fixed maturity securities		1,775	5,125	3,656
Equity securities		0	69	12
Subtotal	[1]	$ 1,775	$ 5,194	$ 3,668

[1] Excludes foreign exchange.