Pension and Other Post-Retirement Plans (Details 3) (USD $)	12 Months Ended			12 Months Ended		12 Months Ended				12 Months Ended					12 Months Ended																					12 Months Ended										12 Months Ended		12 Months Ended
	Dec. 31, 2011	Dec. 31, 2011 U.K. Plan	Dec. 31, 2010 U.K. Plan	Dec. 31, 2011 U.K. Plan Corporate bonds	Dec. 31, 2010 U.K. Plan Corporate bonds	Dec. 31, 2011 U.K. Plan Real estate	Dec. 31, 2010 U.K. Plan Real estate	Dec. 31, 2011 U.K. Plan Cash	Dec. 31, 2010 U.K. Plan Cash	Dec. 31, 2011 U.K. Plan Gobal return fund	Dec. 31, 2011 U.K. Plan Long lease property	Dec. 31, 2011 U.K. Plan U.K Equity securities	Dec. 31, 2010 U.K. Plan U.K Equity securities	Dec. 31, 2010 U.K. Plan U.K Fixed-income U.K. government bonds	Dec. 31, 2011 U.K. Plan Other foreign countries Equity securities	Dec. 31, 2010 U.K. Plan Other foreign countries Equity securities	Dec. 31, 2011 U.K. Plan Quoted Prices in Active Markets for Identical Assets (Level 1)	Dec. 31, 2010 U.K. Plan Quoted Prices in Active Markets for Identical Assets (Level 1)	Dec. 31, 2011 U.K. Plan Quoted Prices in Active Markets for Identical Assets (Level 1) Cash	Dec. 31, 2010 U.K. Plan Quoted Prices in Active Markets for Identical Assets (Level 1) Cash	Dec. 31, 2011 U.K. Plan Significant Observable Inputs (Level 2)	Dec. 31, 2010 U.K. Plan Significant Observable Inputs (Level 2)	Dec. 31, 2011 U.K. Plan Significant Observable Inputs (Level 2) Corporate bonds	Dec. 31, 2010 U.K. Plan Significant Observable Inputs (Level 2) Corporate bonds	Dec. 31, 2011 U.K. Plan Significant Observable Inputs (Level 2) Gobal return fund	Dec. 31, 2011 U.K. Plan Significant Observable Inputs (Level 2) U.K Equity securities	Dec. 31, 2010 U.K. Plan Significant Observable Inputs (Level 2) U.K Equity securities	Dec. 31, 2010 U.K. Plan Significant Observable Inputs (Level 2) U.K Fixed-income U.K. government bonds	Dec. 31, 2011 U.K. Plan Significant Observable Inputs (Level 2) Other foreign countries Equity securities	Dec. 31, 2010 U.K. Plan Significant Observable Inputs (Level 2) Other foreign countries Equity securities	Dec. 31, 2011 U.K. Plan Significant Unobservable Inputs (Level 3)	Dec. 31, 2010 U.K. Plan Significant Unobservable Inputs (Level 3)	Dec. 31, 2009 U.K. Plan Significant Unobservable Inputs (Level 3)	Dec. 31, 2011 U.K. Plan Significant Unobservable Inputs (Level 3) Real estate	Dec. 31, 2010 U.K. Plan Significant Unobservable Inputs (Level 3) Real estate	Dec. 31, 2011 Canadian Plan	Dec. 31, 2010 Canadian Plan	Dec. 31, 2011 Canadian Plan Government bonds	Dec. 31, 2010 Canadian Plan Government bonds	Dec. 31, 2011 Canadian Plan Corporate bonds	Dec. 31, 2010 Canadian Plan Corporate bonds	Dec. 31, 2011 Canadian Plan Other short-term investment	Dec. 31, 2010 Canadian Plan Other short-term investment	Dec. 31, 2011 Canadian Plan Cash and cash equivalents	Dec. 31, 2010 Canadian Plan Cash and cash equivalents	Dec. 31, 2011 Canadian Plan Canada Equity securities	Dec. 31, 2010 Canadian Plan Canada Equity securities	Dec. 31, 2011 Canadian Plan Other foreign countries Equity securities	Dec. 31, 2010 Canadian Plan Other foreign countries Equity securities	Dec. 31, 2011 Canadian Plan Quoted Prices in Active Markets for Identical Assets (Level 1)	Dec. 31, 2010 Canadian Plan Quoted Prices in Active Markets for Identical Assets (Level 1)	Dec. 31, 2011 Canadian Plan Quoted Prices in Active Markets for Identical Assets (Level 1) Government bonds	Dec. 31, 2010 Canadian Plan Quoted Prices in Active Markets for Identical Assets (Level 1) Government bonds	Dec. 31, 2011 Canadian Plan Quoted Prices in Active Markets for Identical Assets (Level 1) Corporate bonds	Dec. 31, 2010 Canadian Plan Quoted Prices in Active Markets for Identical Assets (Level 1) Corporate bonds	Dec. 31, 2011 Canadian Plan Quoted Prices in Active Markets for Identical Assets (Level 1) Cash and cash equivalents	Dec. 31, 2010 Canadian Plan Quoted Prices in Active Markets for Identical Assets (Level 1) Cash and cash equivalents	Dec. 31, 2011 Canadian Plan Quoted Prices in Active Markets for Identical Assets (Level 1) Canada Equity securities	Dec. 31, 2010 Canadian Plan Quoted Prices in Active Markets for Identical Assets (Level 1) Canada Equity securities	Dec. 31, 2011 Canadian Plan Quoted Prices in Active Markets for Identical Assets (Level 1) Other foreign countries Equity securities	Dec. 31, 2010 Canadian Plan Quoted Prices in Active Markets for Identical Assets (Level 1) Other foreign countries Equity securities	Dec. 31, 2011 Canadian Plan Significant Observable Inputs (Level 2)	Dec. 31, 2010 Canadian Plan Significant Observable Inputs (Level 2)	Dec. 31, 2011 Canadian Plan Significant Observable Inputs (Level 2) Other short-term investment	Dec. 31, 2010 Canadian Plan Significant Observable Inputs (Level 2) Other short-term investment	Dec. 31, 2011 Canadian Plan Significant Observable Inputs (Level 2) Canada Equity securities	Dec. 31, 2010 Canadian Plan Significant Observable Inputs (Level 2) Canada Equity securities	Dec. 31, 2011 Canadian Plan Significant Observable Inputs (Level 2) Other foreign countries Equity securities
Amounts included in accumulated other comprehensive income expected to be recognized as components of net periodic pension cost in next fiscal year
Net gain or loss	$ (78,000)
Net prior service cost	885,000
Net amount expected to be recognized	807,000
Target allocations of plan assets
Target allocation in equities (as a percent)												20.00%			15.00%																															32.00%		28.00%
Target allocation in debt securities (as a percent)				10.00%						35.00%																										40.00%
Target allocation in real estate (as a percent)						5.00%					15.00%
Fair value of plan assets
Total pension assets		$ 42,538,000	$ 43,943,000	$ 4,243,000	$ 5,384,000	$ 9,356,000	$ 2,416,000	$ 171,000	$ 189,000	$ 15,386,000		$ 7,056,000	$ 16,785,000	$ 3,963,000	$ 6,326,000	$ 15,206,000	$ 171,000	$ 189,000	$ 171,000	$ 189,000	$ 33,011,000	$ 41,338,000	$ 4,243,000	$ 5,384,000	$ 15,386,000	$ 7,056,000	$ 16,785,000	$ 3,963,000	$ 6,326,000	$ 15,206,000	$ 2,416,000	$ 2,416,000	$ 1,686,000	$ 2,416,000	$ 2,416,000	$ 30,658,000	$ 29,257,000	$ 4,629,000	$ 2,998,000	$ 6,470,000	$ 6,187,000	$ 377,000	$ 1,423,000	$ 254,000	$ 174,000	$ 9,759,000	$ 9,634,000	$ 9,169,000	$ 8,841,000	$ 25,175,000	$ 27,127,000	$ 4,629,000	$ 2,998,000	$ 6,470,000	$ 6,187,000	$ 254,000	$ 174,000	$ 9,049,000	$ 8,927,000	$ 4,773,000	$ 8,841,000	$ 5,483,000	$ 2,130,000	$ 377,000	$ 1,423,000	$ 710,000	$ 707,000	$ 4,396,000