Significant Accounting Policies - Additional Information (Detail) - USD ($) |
3 Months Ended | ||
|---|---|---|---|
Mar. 31, 2022 |
Mar. 31, 2021 |
Dec. 31, 2021 |
|
| Significant Accounting Policies [Line Items] | |||
| Fair value of loaned securities held | $ 13,100,000,000 | $ 13,200,000,000 | |
| Fair value of collateral loan under these securities lending agreements | 14,000,000,000.0 | 14,100,000,000 | |
| Separate account collateral held under securities lending agreements | 7,083,000,000 | $ 7,081,000,000 | |
| Fair value of securities received as collateral have been resold or repledged | 0 | $ 0 | |
| Reduction of management fees | $ 72,000,000 | $ 70,000,000 | |
| Minimum [Member] | |||
| Significant Accounting Policies [Line Items] | |||
| Collateral cash and securities received in exchange of value of securities lent in order to reduce counterparty risk | 102.00% | ||
| Maximum [Member] | |||
| Significant Accounting Policies [Line Items] | |||
| Collateral cash and securities received in exchange of value of securities lent in order to reduce counterparty risk | 112.00% | ||