Fair Value Measurements (Details) - USD ($) $ in Millions	Jun. 30, 2015	Dec. 31, 2014
Assets and Liabilities Measured at Fair Value on a Recurring Basis
Derivatives	$ 45	$ 413
Derivatives	80	84
Fair Value, Measurements, Recurring [Member]
Assets and Liabilities Measured at Fair Value on a Recurring Basis
Marketable Securities	365	422
Derivatives	45	413
Total Assets at Fair Value	410	835
Derivatives	80	84
Total Liabilities at Fair Value	80	84
Fair Value, Measurements, Recurring [Member] | Level 1 [Member]
Assets and Liabilities Measured at Fair Value on a Recurring Basis
Marketable Securities	365	422
Derivatives	22	394
Total Assets at Fair Value	387	816
Derivatives	60	83
Total Liabilities at Fair Value	60	83
Fair Value, Measurements, Recurring [Member] | Level 2 [Member]
Assets and Liabilities Measured at Fair Value on a Recurring Basis
Marketable Securities	0	0
Derivatives	23	19
Total Assets at Fair Value	23	19
Derivatives	20	1
Total Liabilities at Fair Value	20	1
Fair Value, Measurements, Recurring [Member] | Level 3 [Member]
Assets and Liabilities Measured at Fair Value on a Recurring Basis
Marketable Securities	0	0
Derivatives	0	0
Total Assets at Fair Value	0	0
Derivatives	0	0
Total Liabilities at Fair Value	$ 0	$ 0