Summary of Net Operating Income (Loss) for Segments and Corporate and Other Activities (Parenthetical) (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Segment Reporting Information [Line Items]
Adjustment to (gains) losses on extinguishment of debt for portion attributable to noncontrolling interests			$ 1
Net Investment (Gains) Losses
Segment Reporting Information [Line Items]
Adjustment for DAC and other intangibles and certain benefit reserves	$ (3)	$ (14)	(35)
Adjustment for portion attributable to noncontrolling interests	$ 66	$ 20	$ (10)