Recent Accounting Pronouncements Revenue from Contracts with Customers ASU 2014-09 (Details) - Revenue from contracts with customers standard [Member] - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2017	Sep. 30, 2017
Sales Revenue, Net [Member]
Impact of fees previously recorded as a reduction of expenses	$ 33	$ 85
General and administrative expense [Member]
Impact of fees previously recorded as a reduction of expenses	$ 28	$ 80

Represents the quantification of the effect of adopting the new accounting standard or change in accounting principle expected by the entity to have a significant effect on the entity's financial statements.

No definition available.

Name:	us-gaap_NewAccountingPronouncementOrChangeInAccountingPrincipleEffectOfAdoptionQuantification
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration