Variable Interest Entities (Narrative) (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Variable Interest Entity [Line Items]
Carrying amounts of assets	$ 1,700	$ 3,200
Carrying amounts of liabilities	$ 1,700	$ 2,300
Variable Interest Entity Primary Beneficiary [Member] | Structured Finance And International Insurance [Member]
Variable Interest Entity [Line Items]
Number of variable interest entities consolidated	0
Variable Interest Entity Primary Beneficiary [Member] | Structured Finance And International Insurance [Member] | Zohar Funds Bankruptcy Cases Debtors [Member]
Variable Interest Entity [Line Items]
Net realized gains (losses) related to deconsolidation	$ (93)
Number of variable interest entities deconsolidated	2
Variable Interest Entity Primary Beneficiary [Member] | Structured Finance And International Insurance [Member] | Non-Zohar [Member]
Variable Interest Entity [Line Items]
Number of variable interest entities deconsolidated	8