Fair Value Measurements (Narrative) (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments in money market mutual funds classified as cash and cash equivalents	$ 3,300,000,000	$ 2,100,000,000
Fair Value | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt, Fair Value	3,600,000,000
Carrying (Reported) Amount
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt, Fair Value	3,500,000,000
Non - U.S. Pension Benefit | Common stock and equivalents
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities lending arrangement	16,000,000	8,000,000
Non - U.S. Pension Benefit | Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities lending arrangement	12,000,000	13,000,000
U.S. Pension Benefit Plans | Common stock and equivalents
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities lending arrangement		125,000,000
U.S. Pension Benefit Plans | Government, agency and government-sponsored enterprise obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities lending arrangement		199,000,000
U.S. Pension Benefit Plans | Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities lending arrangement		19,000,000
Postretirement Health Care Benefits Plan | Common stock and equivalents
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities lending arrangement		3,000,000
Postretirement Health Care Benefits Plan | Government, agency and government-sponsored enterprise obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities lending arrangement		$ 5,000,000