INVESTMENTS - Repurchase Agreements and Securities Lending (Details) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
U.S. corporate public securities
Assets Sold under Agreements to Repurchase [Line Items]
Securities	$ 1,009	$ 311
Equity securities
Assets Sold under Agreements to Repurchase [Line Items]
Securities	0	106
Overnight & Continuous | Equity securities
Assets Sold under Agreements to Repurchase [Line Items]
Securities	0	106
Up to 30 days | U.S. corporate public securities
Assets Sold under Agreements to Repurchase [Line Items]
Securities	101	111
Up to 30 days | Equity securities
Assets Sold under Agreements to Repurchase [Line Items]
Securities	0	0
30-90 days | U.S. corporate public securities
Assets Sold under Agreements to Repurchase [Line Items]
Securities	414	200
30-90 days | Equity securities
Assets Sold under Agreements to Repurchase [Line Items]
Securities	0	$ 0
1-5 Years | U.S. corporate public securities
Assets Sold under Agreements to Repurchase [Line Items]
Securities	$ 494