Land, Buildings, Equipment and Software, Net - Depreciation Expense, Operating Lease Rent Expense, Minimum Operating Lease Commitments (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Property, Plant and Equipment [Line Items]
Depreciation expense	$ 148	$ 151	$ 179
Operating lease rent expense	157	164	$ 175
Capital Leased Assets, Gross	31	$ 39
Continuing Operations [Member]
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
2017	124
2018	94
2019	72
2020	53
2021	40
Thereafter	$ 71