Derivative and Financial Instruments - FX Notional (Details 5) (Foreign Currency Exchange Derivative [Member]) In Millions, unless otherwise specified	Mar. 31, 2014 Sell U.S. dollar, buy British pound [Member] USD ($)	Mar. 31, 2014 Buy U.S. dollar, sell other currencies [Member] USD ($)		Dec. 31, 2013 Buy U.S. dollar, sell other currencies [Member] USD ($)		Mar. 31, 2014 Buy British pound, sell euro [Member] GBP (£)	Dec. 31, 2013 Buy British pound, sell euro [Member] USD ($)
Trading Activity, Gains and Losses, Net [Line Items]
Net notional position of foreign currency exchange derivatives	$ 250	$ 163	[1]	$ 6	[1]	£ 63	$ 17

[1] *Primarily Canadian dollar and Norwegian krone.