Consolidated Balance Sheets (Parenthetical) (GBP £) In Millions, except Per Share data, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Statement of Financial Position [Abstract]
Common Stock, Par Value	£ 0.05	£ 0.05
Common Stock, Shares Authorized	1,000	1,000
Common Stock, Shares, Issued	562.5	562.5
Common Stock, Shares, Outstanding	562.5	562.5
Treasury Stock, Shares	6.8	11.8