Fair Value of Financial Instruments - Additional Information (Detail) $ in Millions	9 Months Ended
	Sep. 30, 2020 USD ($)	Dec. 31, 2019 USD ($)
Fair Value of Financial Instruments [Line Items]
Available-for-sale debt securities	$ 64,416	$ 60,339
GMWB non-performance risk impact	$ 85	62
Period end valuation	0
Fixed maturity securities | U.S. corporate
Fair Value of Financial Instruments [Line Items]
Available-for-sale debt securities	$ 35,234	32,111
Fixed maturity securities | Non-U.S. corporate
Fair Value of Financial Instruments [Line Items]
Available-for-sale debt securities	11,543	10,525
Level 2
Fair Value of Financial Instruments [Line Items]
Available-for-sale debt securities	60,274	56,148
Level 2 | Fixed maturity securities | U.S. corporate
Fair Value of Financial Instruments [Line Items]
Available-for-sale debt securities	32,994	29,872
Level 2 | Fixed maturity securities | Non-U.S. corporate
Fair Value of Financial Instruments [Line Items]
Available-for-sale debt securities	$ 9,893	8,840
Level 2 | Fixed maturity securities | Third-Party Pricing Services
Fair Value of Financial Instruments [Line Items]
Percentage of available for sale debt securities	91.00%
Level 2 | Fixed maturity securities | Third-Party Pricing Services | U.S. corporate
Fair Value of Financial Instruments [Line Items]
Available-for-sale debt securities	$ 31,695
Level 2 | Fixed maturity securities | Third-Party Pricing Services | Non-U.S. corporate
Fair Value of Financial Instruments [Line Items]
Available-for-sale debt securities	9,220
Level 2 | Fixed maturity securities | Internal models | U.S. corporate
Fair Value of Financial Instruments [Line Items]
Available-for-sale debt securities	1,299
Level 2 | Fixed maturity securities | Internal models | Non-U.S. corporate
Fair Value of Financial Instruments [Line Items]
Available-for-sale debt securities	673
Level 3
Fair Value of Financial Instruments [Line Items]
Available-for-sale debt securities	4,142	4,191
Level 3 | Fixed maturity securities | U.S. corporate
Fair Value of Financial Instruments [Line Items]
Available-for-sale debt securities	2,240	2,239
Level 3 | Fixed maturity securities | Non-U.S. corporate
Fair Value of Financial Instruments [Line Items]
Available-for-sale debt securities	1,650	$ 1,685
Level 3 | Fixed maturity securities | Internal models
Fair Value of Financial Instruments [Line Items]
Available-for-sale debt securities	3,314
Level 3 | Fixed maturity securities | Broker Quotes
Fair Value of Financial Instruments [Line Items]
Available-for-sale debt securities	$ 828