Investments in fixed maturity securities - Carrying value by segment (Detail) - USD ($) $ in Millions		Sep. 30, 2017	Dec. 31, 2016
Summary of Investment Holdings [Line Items]
Investments in fixed maturity securities		$ 22,256	$ 23,465
Insurance and Other [Member]
Summary of Investment Holdings [Line Items]
Investments in fixed maturity securities		22,228	23,432
Finance and Financial Products [Member] | Other Assets [Member]
Summary of Investment Holdings [Line Items]
Investments in fixed maturity securities	[1]	$ 28	$ 33

[1] Included in other assets.