Fair Value Hierarchy - Schedule of Level 3 Assets, and Ranges and Weighted Averages of Significant Unobservable Inputs (Detail) $ in Millions	Dec. 31, 2022 USD ($) yr	Dec. 31, 2021 USD ($) yr
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Total financial assets at fair value | $	$ 650,966	$ 715,812
Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Total financial assets at fair value | $	26,048	24,083
Level 3 | Loans and securities backed by real estate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Total financial assets at fair value | $	$ 154	$ 289
Level 3 | Loans and securities backed by real estate | Minimum | Yield
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	0.030	0.004
Level 3 | Loans and securities backed by real estate | Minimum | Recovery rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	0.358	0.051
Level 3 | Loans and securities backed by real estate | Minimum | Cumulative loss rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	0.037	0.001
Level 3 | Loans and securities backed by real estate | Minimum | Duration (years)
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	0.9	0.1
Level 3 | Loans and securities backed by real estate | Maximum | Yield
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	0.360	0.285
Level 3 | Loans and securities backed by real estate | Maximum | Recovery rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	0.761	0.865
Level 3 | Loans and securities backed by real estate | Maximum | Cumulative loss rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	0.299	0.434
Level 3 | Loans and securities backed by real estate | Maximum | Duration (years)
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	12.3	17.2
Level 3 | Loans and securities backed by real estate | Weighted Average | Yield
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	0.142	0.097
Level 3 | Loans and securities backed by real estate | Weighted Average | Recovery rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	0.547	0.550
Level 3 | Loans and securities backed by real estate | Weighted Average | Cumulative loss rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	0.104	0.177
Level 3 | Loans and securities backed by real estate | Weighted Average | Duration (years)
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	4.6	4.3
Level 3 | Corporate debt instruments
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Total financial assets at fair value | $	$ 1,238	$ 1,318
Level 3 | Corporate debt instruments | Minimum | Yield
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	0.011	0.000
Level 3 | Corporate debt instruments | Minimum | Recovery rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	0.115	0.090
Level 3 | Corporate debt instruments | Minimum | Duration (years)
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	0.3	2.0
Level 3 | Corporate debt instruments | Maximum | Yield
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	0.343	0.180
Level 3 | Corporate debt instruments | Maximum | Recovery rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	0.770	0.699
Level 3 | Corporate debt instruments | Maximum | Duration (years)
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	20.3	28.5
Level 3 | Corporate debt instruments | Weighted Average | Yield
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	0.069	0.071
Level 3 | Corporate debt instruments | Weighted Average | Recovery rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	0.480	0.520
Level 3 | Corporate debt instruments | Weighted Average | Duration (years)
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	4.5	4.5
Level 3 | Other
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Total financial assets at fair value | $	$ 342	$ 282
Level 3 | Other | Minimum | Yield
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	0.028	0.011
Level 3 | Other | Minimum | Recovery rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	3.3
Level 3 | Other | Minimum | Duration (years)
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	1.2	0.9
Level 3 | Other | Maximum | Yield
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	0.478	0.448
Level 3 | Other | Maximum | Recovery rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	4.5
Level 3 | Other | Maximum | Duration (years)
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	14.4	5.2
Level 3 | Other | Weighted Average | Yield
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	0.100	0.094
Level 3 | Other | Weighted Average | Recovery rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	4.3
Level 3 | Other | Weighted Average | Duration (years)
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement input	6.1	2.4