Commitments and Contingencies (Details 3) (USD $) In Millions, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Fair values of plan assets for each major asset category based on the nature and significant concentration of risks in plan assets
Fair value of plan assets	$ 145	$ 135
Quoted Price in Active Markets (Level 1) [Member]
Fair values of plan assets for each major asset category based on the nature and significant concentration of risks in plan assets
Fair value of plan assets	145	135
Significant Other Inputs (Level 2) [Member]
Fair values of plan assets for each major asset category based on the nature and significant concentration of risks in plan assets
Fair value of plan assets	0	0
Unobservable Inputs (Level 3) [Member]
Fair values of plan assets for each major asset category based on the nature and significant concentration of risks in plan assets
Fair value of plan assets	0	0
Equity Securities [Member]
Fair values of plan assets for each major asset category based on the nature and significant concentration of risks in plan assets
Fair value of plan assets	70	70
Equity Securities [Member] | Quoted Price in Active Markets (Level 1) [Member]
Fair values of plan assets for each major asset category based on the nature and significant concentration of risks in plan assets
Fair value of plan assets	70	70
Equity Securities [Member] | Significant Other Inputs (Level 2) [Member]
Fair values of plan assets for each major asset category based on the nature and significant concentration of risks in plan assets
Fair value of plan assets	0	0
Equity Securities [Member] | Unobservable Inputs (Level 3) [Member]
Fair values of plan assets for each major asset category based on the nature and significant concentration of risks in plan assets
Fair value of plan assets	0	0
UK Quoted Equities [Member]
Fair values of plan assets for each major asset category based on the nature and significant concentration of risks in plan assets
Fair value of plan assets	24	24
UK Quoted Equities [Member] | Quoted Price in Active Markets (Level 1) [Member]
Fair values of plan assets for each major asset category based on the nature and significant concentration of risks in plan assets
Fair value of plan assets	24	24
UK Quoted Equities [Member] | Significant Other Inputs (Level 2) [Member]
Fair values of plan assets for each major asset category based on the nature and significant concentration of risks in plan assets
Fair value of plan assets	0	0
UK Quoted Equities [Member] | Unobservable Inputs (Level 3) [Member]
Fair values of plan assets for each major asset category based on the nature and significant concentration of risks in plan assets
Fair value of plan assets	0	0
Overseas Quoted Equities [Member]
Fair values of plan assets for each major asset category based on the nature and significant concentration of risks in plan assets
Fair value of plan assets	46	46
Overseas Quoted Equities [Member] | Quoted Price in Active Markets (Level 1) [Member]
Fair values of plan assets for each major asset category based on the nature and significant concentration of risks in plan assets
Fair value of plan assets	46	46
Overseas Quoted Equities [Member] | Significant Other Inputs (Level 2) [Member]
Fair values of plan assets for each major asset category based on the nature and significant concentration of risks in plan assets
Fair value of plan assets	0	0
Overseas Quoted Equities [Member] | Unobservable Inputs (Level 3) [Member]
Fair values of plan assets for each major asset category based on the nature and significant concentration of risks in plan assets
Fair value of plan assets	0	0
Debt Securities [Member]
Fair values of plan assets for each major asset category based on the nature and significant concentration of risks in plan assets
Fair value of plan assets	69	65
Debt Securities [Member] | Quoted Price in Active Markets (Level 1) [Member]
Fair values of plan assets for each major asset category based on the nature and significant concentration of risks in plan assets
Fair value of plan assets	69	65
Debt Securities [Member] | Significant Other Inputs (Level 2) [Member]
Fair values of plan assets for each major asset category based on the nature and significant concentration of risks in plan assets
Fair value of plan assets	0	0
Debt Securities [Member] | Unobservable Inputs (Level 3) [Member]
Fair values of plan assets for each major asset category based on the nature and significant concentration of risks in plan assets
Fair value of plan assets	0	0
U.K. Government bonds [Member]
Fair values of plan assets for each major asset category based on the nature and significant concentration of risks in plan assets
Fair value of plan assets	43	42
U.K. Government bonds [Member] | Quoted Price in Active Markets (Level 1) [Member]
Fair values of plan assets for each major asset category based on the nature and significant concentration of risks in plan assets
Fair value of plan assets	43	42
U.K. Government bonds [Member] | Significant Other Inputs (Level 2) [Member]
Fair values of plan assets for each major asset category based on the nature and significant concentration of risks in plan assets
Fair value of plan assets	0	0
U.K. Government bonds [Member] | Unobservable Inputs (Level 3) [Member]
Fair values of plan assets for each major asset category based on the nature and significant concentration of risks in plan assets
Fair value of plan assets	0	0
U.K. corporate bonds [Member]
Fair values of plan assets for each major asset category based on the nature and significant concentration of risks in plan assets
Fair value of plan assets	26	23
U.K. corporate bonds [Member] | Quoted Price in Active Markets (Level 1) [Member]
Fair values of plan assets for each major asset category based on the nature and significant concentration of risks in plan assets
Fair value of plan assets	26	23
U.K. corporate bonds [Member] | Significant Other Inputs (Level 2) [Member]
Fair values of plan assets for each major asset category based on the nature and significant concentration of risks in plan assets
Fair value of plan assets	0	0
U.K. corporate bonds [Member] | Unobservable Inputs (Level 3) [Member]
Fair values of plan assets for each major asset category based on the nature and significant concentration of risks in plan assets
Fair value of plan assets	0	0
Cash [Member]
Fair values of plan assets for each major asset category based on the nature and significant concentration of risks in plan assets
Fair value of plan assets	6	0
Cash [Member] | Quoted Price in Active Markets (Level 1) [Member]
Fair values of plan assets for each major asset category based on the nature and significant concentration of risks in plan assets
Fair value of plan assets	6	0
Cash [Member] | Significant Other Inputs (Level 2) [Member]
Fair values of plan assets for each major asset category based on the nature and significant concentration of risks in plan assets
Fair value of plan assets	0	0
Cash [Member] | Unobservable Inputs (Level 3) [Member]
Fair values of plan assets for each major asset category based on the nature and significant concentration of risks in plan assets
Fair value of plan assets	$ 0	$ 0