Investments in Debt and Equity Securities (Details 3) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Investments, Debt and Equity Securities [Abstract]
Due in one year or less, Cost Basis	$ 146		$ 146
Due after one year through five years, Cost Basis	725		725
Due after five through ten years, Cost Basis	284		284
Due after ten years, Cost Basis	53		53
Due in one year or less, Fair Value	148		148
Due after one year through five years, Fair Value	753		753
Due after five years through ten years, Fair Value	292		292
Due after ten years, Fair Value	55		55
Debt Securities, Available-for-sale, Amortized Cost	1,639		1,639		$ 1,613
Available-for-sale securities, debt securities	1,691		1,691		1,683
Schedule of Investments in Debt and Equity Securities
Unrealized gain (loss) on equity securities	21	$ 26	38	$ (14)
Available-for-sale Securities, Proceeds, Gains and Losses
Proceeds from the sale of available-for-sale securities	125	66	225	124
Gross gains from the sale of available-for-sale securities	2	1	2	1
Gross losses from the sale of available-for-sale securities	0	$ 1	0	$ 1
U.S. governmental agency mortgage-backed securities
Investments, Debt and Equity Securities [Abstract]
Debt Securities, Available-for-sale, Amortized Cost	346		346		362
Available-for-sale securities, debt securities	355		355		374
Residential
Investments, Debt and Equity Securities [Abstract]
Debt Securities, Available-for-sale, Amortized Cost	5		5		5
Available-for-sale securities, debt securities	5		5		5
Commercial
Investments, Debt and Equity Securities [Abstract]
Debt Securities, Available-for-sale, Amortized Cost	80		80		60
Available-for-sale securities, debt securities	$ 83		$ 83		$ 64