Investments in Debt and Equity Securities (Details 3) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Investments, Debt and Equity Securities [Abstract]
Due in one year or less, Cost Basis	$ 134		$ 134
Due after one year through five years, Cost Basis	715		715
Due after five through ten years, Cost Basis	246		246
Due after ten years, Cost Basis	85		85
Due in one year or less, Fair Value	135		135
Due after one year through five years, Fair Value	748		748
Due after five years through ten years, Fair Value	257		257
Due after ten years, Fair Value	86		86
Debt Securities, Available-for-sale, Amortized Cost	1,597		1,597		$ 1,340
Available-for-sale securities, debt securities	1,660		1,660		1,365
Schedule of Investments in Debt and Equity Securities
Unrealized gain (loss) on equity securities	9	$ 2	(1)	$ 54
Available-for-sale Securities, Proceeds, Gains and Losses
Proceeds from the sale of available-for-sale securities	74	92	197	237
Gross gains from the sale of available-for-sale securities	0	0	1	1
Gross losses from the sale of available-for-sale securities	0	$ 0	1	$ 1
U.S. governmental agency mortgage-backed securities
Investments, Debt and Equity Securities [Abstract]
Debt Securities, Available-for-sale, Amortized Cost	351		351		327
Available-for-sale securities, debt securities	364		364		331
Residential
Investments, Debt and Equity Securities [Abstract]
Debt Securities, Available-for-sale, Amortized Cost	5		5		6
Available-for-sale securities, debt securities	5		5		6
Commercial
Investments, Debt and Equity Securities [Abstract]
Debt Securities, Available-for-sale, Amortized Cost	61		61		46
Available-for-sale securities, debt securities	$ 65		$ 65		$ 47