Income Taxes (Details 5) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012
Operating and capital loss carryforwards
Benefit realized from tax holiday granted	$ 11
U.K.
Operating and capital loss carryforwards
Operating loss carryforwards	552
Capital loss carryforwards	251
U.S. Federal
Operating and capital loss carryforwards
Operating loss carryforwards	25
U.S. State
Operating and capital loss carryforwards
Operating loss carryforwards	605
Other
Operating and capital loss carryforwards
Operating loss carryforwards	283
Capital loss carryforwards	$ 65