Investments (Variable Interest Entities - Narrative) (Details) - RMBS - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2021
Variable Interest Entity [Line Items]
Proceeds from securitization of loan held for investment carrying value	$ 308
Proceeds from Securitizations of Loans Held-for-investment	313
Gain (Loss) on Securitization of Financial Assets	5	$ 24
Transfers of Financial Assets Accounted for as Sale, Initial Fair Value of Assets Obtained as Proceeds	$ 43		$ 0