Activity Associated with Derivative Instruments (Detail) $ in Millions	9 Months Ended
	Sep. 30, 2023 USD ($) Policies
Derivative [Line Items]
Notional amount, beginning balance	$ 11,025
Additions	6,504
Maturities/ terminations	(5,307)
Notional amount, ending balance	12,222
Designated As Hedging Instrument
Derivative [Line Items]
Notional amount, beginning balance	8,686
Additions	1,275
Maturities/ terminations	(274)
Notional amount, ending balance	9,687
Designated As Hedging Instrument | Cash Flow Hedges
Derivative [Line Items]
Notional amount, beginning balance	8,686
Additions	1,275
Maturities/ terminations	(274)
Notional amount, ending balance	9,687
Designated As Hedging Instrument | Cash Flow Hedges | Interest rate swaps
Derivative [Line Items]
Notional amount, beginning balance	8,542
Additions	1,200
Maturities/ terminations	(261)
Notional amount, ending balance	9,481
Designated As Hedging Instrument | Cash Flow Hedges | Foreign currency swaps
Derivative [Line Items]
Notional amount, beginning balance	144
Additions	0
Maturities/ terminations	(13)
Notional amount, ending balance	131
Designated As Hedging Instrument | Forward bond purchase commitments | Cash Flow Hedges
Derivative [Line Items]
Notional amount, beginning balance	0
Additions	75
Maturities/ terminations	0
Notional amount, ending balance	75
Derivatives not designated as hedges
Derivative [Line Items]
Notional amount, beginning balance	2,339
Additions	5,229
Maturities/ terminations	(5,033)
Notional amount, ending balance	2,535
Derivatives not designated as hedges | Equity index options
Derivative [Line Items]
Notional amount, beginning balance	936
Additions	513
Maturities/ terminations	(682)
Notional amount, ending balance	767
Derivatives not designated as hedges | Financial futures
Derivative [Line Items]
Notional amount, beginning balance	1,403
Additions	4,216
Maturities/ terminations	(4,351)
Notional amount, ending balance	$ 1,268
Derivatives not designated as hedges | Fixed indexed annuity embedded derivatives
Derivative [Line Items]
Notional amount, beginning balance | Policies	7,315
Additions | Policies	0
Maturities/ terminations | Policies	(1,177)
Notional amount, ending balance | Policies	6,138
Derivatives not designated as hedges | Indexed universal life embedded derivatives
Derivative [Line Items]
Notional amount, beginning balance | Policies	771
Additions | Policies	0
Maturities/ terminations | Policies	(22)
Notional amount, ending balance | Policies	749
Derivatives not designated as hedges | Forward bond purchase commitments
Derivative [Line Items]
Notional amount, beginning balance	$ 0
Additions	500
Maturities/ terminations	0
Notional amount, ending balance	$ 500