Fair Value Measurements (Schedule Of Significant Unobservable Inputs Used In Level 3 Liability Valuations) (Detail) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2021		Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Minimum
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Long-Duration Contracts, Assumptions by Product and Guarantee, Lapse Rate		3.00%
Annuitization rate		0.00%
Maximum
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Long-Duration Contracts, Assumptions by Product and Guarantee, Lapse Rate		31.00%
Annuitization rate		100.00%
Weighted Average
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Long-Duration Contracts, Assumptions by Product and Guarantee, Lapse Rate		4.50%
Annuitization rate	[1]	3.60%
Level 3 | Equity Securities [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Settlements, assets		$ 0		$ 0	$ 0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Period Increase (Decrease)		0		0	0
Change in Net Unrealized Gains/Losses included in OCI at the Balance Sheet Date, Assets		0		0	0
Level 3 | Short-term investments
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Settlements, assets		(6)		(12)	(1)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Period Increase (Decrease)		0		0	0
Change in Net Unrealized Gains/Losses included in OCI at the Balance Sheet Date, Assets		0		0	0
Level 3 | Other Long-term Investments [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Settlements, assets		0		0	(1)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Period Increase (Decrease)		0		0	0
Change in Net Unrealized Gains/Losses included in OCI at the Balance Sheet Date, Assets		0		0	0
Level 3 | Fixed maturities available for sale | Debt Security, Government, Non-US [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Settlements, assets		(122)		(57)	(53)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Period Increase (Decrease)		0		0	0
Change in Net Unrealized Gains/Losses included in OCI at the Balance Sheet Date, Assets		(25)		16	7
Level 3 | Fixed maturities available for sale | Corporate securities
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Settlements, assets		(607)		(423)	(279)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Period Increase (Decrease)		0		0	0
Change in Net Unrealized Gains/Losses included in OCI at the Balance Sheet Date, Assets		17		(6)	(8)
Level 3 | Fixed maturities available for sale | Mortgage-backed securities
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Settlements, assets		(33)		(1)	(3)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Period Increase (Decrease)		0		0	0
Change in Net Unrealized Gains/Losses included in OCI at the Balance Sheet Date, Assets		0		0	0
Guaranteed Minimum Income Benefit | Level 3
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability Value		745	[2]	1,089	897	$ 861
Settlements, liabilities		0		0	0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Period Increase (Decrease)		(28)		(10)	32
Fair Value, Liability, Recurring Basis, Still Held, Unrealized Gain (Loss), OCI		0		$ 0	$ 0
Guaranteed Minimum Income Benefit | Level 3 | Fair Value, Recurring [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability Value		$ 745

[1] The weighted average lapse and annuitization rates are determined by weighting each treaty's rates by the GLB contracts fair value.

[2] Our GLB reinsurance product meets the definition of a derivative instrument for accounting purposes and is accordingly carried at fair value.