Liabilities by Class of Instrument that are Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Millions		Dec. 31, 2018	Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities, fair value		$ 906	$ 730
Total liabilities		906	730
Other liabilities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities, fair value		168	47
Other liabilities | Interest rate swaps
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities, fair value		102	25
Other liabilities | Foreign currency swaps
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities, fair value		23
Other liabilities | Other foreign currency contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities, fair value		42	20
Other liabilities | Equity return swaps
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities, fair value		1	2
Policyholder account balances
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities, fair value		738	683
Policyholder account balances | GMWB embedded derivatives
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities, fair value	[1]	337	250
Policyholder account balances | Fixed index annuity embedded derivatives
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities, fair value		389	419
Policyholder account balances | Indexed universal life embedded derivatives
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities, fair value		12	14
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total liabilities		0	0
Level 1 | Other liabilities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities, fair value		0	0
Level 1 | Other liabilities | Interest rate swaps
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities, fair value		0	0
Level 1 | Other liabilities | Foreign currency swaps
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities, fair value		0
Level 1 | Other liabilities | Other foreign currency contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities, fair value		0	0
Level 1 | Other liabilities | Equity return swaps
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities, fair value		0	0
Level 1 | Policyholder account balances
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities, fair value		0	0
Level 1 | Policyholder account balances | GMWB embedded derivatives
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities, fair value	[1]	0	0
Level 1 | Policyholder account balances | Fixed index annuity embedded derivatives
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities, fair value		0	0
Level 1 | Policyholder account balances | Indexed universal life embedded derivatives
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities, fair value		0	0
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total liabilities		168	47
Level 2 | Other liabilities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities, fair value		168	47
Level 2 | Other liabilities | Interest rate swaps
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities, fair value		102	25
Level 2 | Other liabilities | Foreign currency swaps
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities, fair value		23
Level 2 | Other liabilities | Other foreign currency contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities, fair value		42	20
Level 2 | Other liabilities | Equity return swaps
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities, fair value		1	2
Level 2 | Policyholder account balances
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities, fair value		0	0
Level 2 | Policyholder account balances | GMWB embedded derivatives
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities, fair value	[1]	0	0
Level 2 | Policyholder account balances | Fixed index annuity embedded derivatives
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities, fair value		0	0
Level 2 | Policyholder account balances | Indexed universal life embedded derivatives
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities, fair value		0	0
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total liabilities		738	683
Level 3 | Other liabilities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities, fair value		0	0
Level 3 | Other liabilities | Interest rate swaps
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities, fair value		0	0
Level 3 | Other liabilities | Foreign currency swaps
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities, fair value		0
Level 3 | Other liabilities | Other foreign currency contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities, fair value		0	0
Level 3 | Other liabilities | Equity return swaps
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities, fair value		0	0
Level 3 | Policyholder account balances
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities, fair value		738	683
Level 3 | Policyholder account balances | GMWB embedded derivatives
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities, fair value	[1]	337	250
Level 3 | Policyholder account balances | Fixed index annuity embedded derivatives
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities, fair value		389	419
Level 3 | Policyholder account balances | Indexed universal life embedded derivatives
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities, fair value		$ 12	$ 14

[1] Represents embedded derivatives associated with our GMWB liabilities, excluding the impact of reinsurance.