New Accounting Pronouncements (Details) - USD ($) $ in Millions		Dec. 31, 2016	Dec. 31, 2015
New Accounting Pronouncement, Early Adoption [Line Items]
Cumulative effect of new accounting principle	[1]	$ (19)	$ 0
Accounting Standards Update 2016-01 [Member] | Adjustments for New Accounting Principle, Early Adoption [Member] | Accumulated other comprehensive income (loss)
New Accounting Pronouncement, Early Adoption [Line Items]
Cumulative effect of new accounting principle		(19)	0
Accounting Standards Update 2016-01 [Member] | Adjustments for New Accounting Principle, Early Adoption [Member] | Accumulated deficit
New Accounting Pronouncement, Early Adoption [Line Items]
Cumulative effect of new accounting principle		19	0
Accounting Standards Update 2016-09 [Member] | Adjustments for New Accounting Principle, Early Adoption [Member] | Accumulated deficit
New Accounting Pronouncement, Early Adoption [Line Items]
Cumulative effect of new accounting principle		$ 4	$ 0

[1] For information on the adoption of new accounting guidance related to fair value option debt attributable to our credit spreads, see Note 13, "New Accounting Pronouncements."