Gains and Losses Included in Net (Income) from Liabilities Measured at Fair Value (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Total realized and unrealized (gains) losses included in net (income) loss, liabilities	$ 47	$ 31	$ (6)
Total (gains) losses included in net (income) loss attributable to liabilities still held, liabilities	52	33	(4)
Net Investment Income
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Total realized and unrealized (gains) losses included in net (income) loss, liabilities	0	0	0
Total (gains) losses included in net (income) loss attributable to liabilities still held, liabilities	0	0	0
Net investment (gains) losses
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Total realized and unrealized (gains) losses included in net (income) loss, liabilities	47	31	(6)
Total (gains) losses included in net (income) loss attributable to liabilities still held, liabilities	$ 52	$ 33	$ (4)