Fair Value Financial Instruments Not Required to Be Carried at Fair Value (Detail) - USD ($) $ in Millions		Jun. 30, 2022	Dec. 31, 2021
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Commercial mortgage loans		$ 7,065	$ 6,830
Liabilities:
Long-term borrowings		1,773	1,899
Off-balance sheet risk		1,409	1,185
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Commercial mortgage loans	[1]	0	0
Bank loan investments	[1]	0	0
Liabilities:
Long-term borrowings	[1]	0	0
Investment contracts	[1]	0	0
Level 1 | Commitments to fund bank loan investments
Liabilities:
Off-balance sheet risk		0	0
Level 1 | Ordinary course of business lending commitments
Liabilities:
Off-balance sheet risk		0	0
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Commercial mortgage loans	[1]	0	0
Bank loan investments	[1]	0	0
Liabilities:
Long-term borrowings	[1]	1,336	1,767
Investment contracts	[1]	0	0
Level 2 | Commitments to fund bank loan investments
Liabilities:
Off-balance sheet risk		0	0
Level 2 | Ordinary course of business lending commitments
Liabilities:
Off-balance sheet risk		0	0
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Commercial mortgage loans	[1]	6,679	7,224
Bank loan investments	[1]	402	370
Liabilities:
Long-term borrowings	[1]	0	0
Investment contracts	[1]	8,146	9,352
Level 3 | Commitments to fund bank loan investments
Liabilities:
Off-balance sheet risk		0	0
Level 3 | Ordinary course of business lending commitments
Liabilities:
Off-balance sheet risk		0	0
Carrying value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Commercial mortgage loans	[1]	7,065	6,830
Bank loan investments	[1]	406	363
Liabilities:
Long-term borrowings	[1]	1,773	1,899
Investment contracts	[1]	8,071	8,657
Carrying value | Commitments to fund bank loan investments
Liabilities:
Off-balance sheet risk		0	0
Carrying value | Ordinary course of business lending commitments
Liabilities:
Off-balance sheet risk		0	0
Fair value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Commercial mortgage loans	[1]	6,679	7,224
Bank loan investments	[1]	402	370
Liabilities:
Long-term borrowings	[1]	1,336	1,767
Investment contracts	[1]	8,146	9,352
Fair value | Commitments to fund bank loan investments
Liabilities:
Off-balance sheet risk		0	0
Fair value | Ordinary course of business lending commitments
Liabilities:
Off-balance sheet risk		0	0
Notional amount | Commitments to fund bank loan investments
Liabilities:
Off-balance sheet risk		75	141
Notional amount | Ordinary course of business lending commitments
Liabilities:
Off-balance sheet risk		$ 88	$ 125

[1] These financial instruments do not have notional amounts.