Leases (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
Year 1 Operating	$ 40
Year 2 Operating	33
Year 3 Operating	26
Year 4 Operating	24
Year 5 Operating	24
Later years, Operating Leases	32
Sublease rentals	(3)
Operating Leases, Future Minimum Payments Due	176
Capital Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
Year 1 Capital	1
Year 2 Capital	1
Year 3 Capital	1
Year 4 Capital	1
Year 5 Capital	1
Later years, Capital Leases	19
Capital Leases, Future Minimum Sublease Rentals	0
Capital Leases, Future Minimum Payments Due	24
Less imputed interest costs	(15)
Capital Leases, Future Minimum Payments, Present Value of Net Minimum Payments	9
Operating Leases, Rent Expense, Net [Abstract]
Operating Leases, Rent Expense	$ 120	$ 105	$ 98