Financing Financing (Other) (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Debt Disclosure [Abstract]
Long-term debt, maturities, repayments of principal in next twelve months	$ 845
Long-term debt, maturities, repayments of principal in year two	646
Long-term debt, maturities, repayments of principal in year three	1,000
Long-term debt, maturities, repayments of principal in year four	1,400
Long-term debt, maturities, repayments of principal in year five	4,900
Long-term debt, maturities, repayments of principal after year five	4,100
Interest paid	$ 126	$ 118	$ 151