Investments in Debt and Equity Securities (Details 3) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Investments, Debt and Equity Securities [Abstract]
Due in one year or less, Cost Basis	$ 97
Due after one year through five years, Cost Basis	683
Due after five through ten years, Cost Basis	189
Due after ten years, Cost Basis	53
Due in one year or less, Fair Value	97
Due after one year through five years, Fair Value	680
Due after five years through ten years, Fair Value	184
Due after ten years, Fair Value	52
Debt Securities, Available-for-sale, Amortized Cost	1,446		$ 1,340
Available-for-sale securities, debt securities	1,449		1,365
Schedule of Investments in Debt and Equity Securities
Unrealized gain (loss) on equity securities	(54)	$ 38
Available-for-sale Securities, Proceeds, Gains and Losses
Proceeds from the sale of available-for-sale securities	58	47
Gross losses from the sale of available-for-sale securities	0	$ 1
U.S. governmental agency mortgage-backed securities
Investments, Debt and Equity Securities [Abstract]
Debt Securities, Available-for-sale, Amortized Cost	365		327
Available-for-sale securities, debt securities	378		331
Residential
Investments, Debt and Equity Securities [Abstract]
Debt Securities, Available-for-sale, Amortized Cost	6		6
Available-for-sale securities, debt securities	5		6
Commercial
Investments, Debt and Equity Securities [Abstract]
Debt Securities, Available-for-sale, Amortized Cost	53		46
Available-for-sale securities, debt securities	$ 53		$ 47