Derivatives and Hedging Activities - Credit Derivatives Sold and Held (Details) - USD ($) $ in Millions	6 Months Ended	12 Months Ended
	Jun. 30, 2021	Dec. 31, 2020
Credit Derivatives [Line Items]
Notional Amount	$ 160	$ 227
Payment / Performance Risk	0.00%	0.00%
Other
Credit Derivatives [Line Items]
Notional Amount	$ 160	$ 227
Average Term (Years)	12 years 8 months 26 days	12 years 9 months 3 days
Payment / Performance Risk	18.14%	19.53%