Investment Securities (Details 1) - USD ($) $ in Millions	3 Months Ended	9 Months Ended	12 Months Ended
	Sep. 30, 2016	Sep. 30, 2016	Dec. 31, 2015
Available-for-sale investment securities with gross unrealized losses and length of time
Estimated Fair Value, Less than 12 months	$ 0	$ 0	$ 452
Estimated Fair Value, 12 months or more	33	33	46
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses [Abstract]
Gross Unrealized Losses, Less than 12 months		0	(5)
Gross Unrealized Losses, 12 months or more		(1)	(4)
U.S. States and Political Subdivisions Debt Securities [Member]
Available-for-sale investment securities with gross unrealized losses and length of time
Estimated Fair Value, Less than 12 months	0	0	100
Estimated Fair Value, 12 months or more	0	0	13
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses [Abstract]
Gross Unrealized Losses, Less than 12 months	0		(3)
Gross Unrealized Losses, 12 months or more	0		(2)
Foreign government bonds and obligations [Member]
Available-for-sale investment securities with gross unrealized losses and length of time
Estimated Fair Value, Less than 12 months	0	0	99
Estimated Fair Value, 12 months or more	0	0	0
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses [Abstract]
Gross Unrealized Losses, Less than 12 months	0		(1)
Gross Unrealized Losses, 12 months or more	0		0
U.S. Government agency obligations [Member]
Available-for-sale investment securities with gross unrealized losses and length of time
Estimated Fair Value, Less than 12 months	0	0	253
Estimated Fair Value, 12 months or more	0	0	0
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses [Abstract]
Gross Unrealized Losses, Less than 12 months	0		(1)
Gross Unrealized Losses, 12 months or more	0		0
Other [Member]
Available-for-sale investment securities with gross unrealized losses and length of time
Estimated Fair Value, Less than 12 months	0	0	0
Estimated Fair Value, 12 months or more	33	$ 33	33
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses [Abstract]
Gross Unrealized Losses, Less than 12 months	0		0
Gross Unrealized Losses, 12 months or more	$ (1)		$ (2)