Derivatives Derivatives - Offsetting Assets and Liabilities (Details) - USD ($) $ in Millions	Sep. 30, 2016	Dec. 31, 2015
Derivative
Net derivative contracts, hedge derivatives, net	$ (327)	$ (581)
Hedge Derivatives Asset
Derivative
Net derivative contracts, assets	10	143
Other assets
Derivative
Net derivative contracts, assets	7	21
Hedge Derivatives Liability
Derivative
Net derivative contracts, liabilities	(238)	(737)
Other Noncurrent Liabilities
Derivative
Net derivative contracts, liabilities	$ (106)	$ (8)