Restructuring Charges (Narrative) (Details) $ in Millions	1 Months Ended	12 Months Ended
	Mar. 31, 2015 USD ($)	Dec. 31, 2016 USD ($) employee	Dec. 31, 2015 USD ($) employee	Dec. 31, 2014 USD ($)	Jun. 30, 2016 USD ($)
Restructuring Cost and Reserve [Line Items]
Estimated recognize pre-tax restructuring charges					$ 213
Expected annualized savings		$ 36
Restructuring charges		41	$ 172	$ 0
Rebranding of Trade Name
Restructuring Cost and Reserve [Line Items]
Restructuring charges	$ 119	0	119
Severance
Restructuring Cost and Reserve [Line Items]
Restructuring charges		$ 22	$ 25
Number of positions eliminated | employee		201	230
Release of sublease loss reserve		$ 17
Facility Consolidation
Restructuring Cost and Reserve [Line Items]
Restructuring charges			$ 10
Facilities-related
Restructuring Cost and Reserve [Line Items]
Restructuring charges		1	0
Release of sublease loss reserve			10
Asset impairments
Restructuring Cost and Reserve [Line Items]
Restructuring charges		$ 8	$ 18