Pension and Other Post-Retirement Plans (Details 3) (USD $) In Thousands, unless otherwise specified	12 Months Ended			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, 2012	Dec. 31, 2012 U.K. Plan	Dec. 31, 2011 U.K. Plan	Dec. 31, 2012 U.K. Plan Gobal return fund		Dec. 31, 2011 U.K. Plan Gobal return fund		Dec. 31, 2012 U.K. Plan Corporate bonds		Dec. 31, 2011 U.K. Plan Corporate bonds		Dec. 31, 2011 U.K. Plan Real estate		Dec. 31, 2012 U.K. Plan Real estate	Dec. 31, 2012 U.K. Plan Cash		Dec. 31, 2011 U.K. Plan Cash		Dec. 31, 2012 U.K. Plan Long lease property	Dec. 31, 2012 U.K. Plan U.K Equity securities		Dec. 31, 2011 U.K. Plan U.K Equity securities		Dec. 31, 2012 U.K. Plan Other foreign countries Equity securities		Dec. 31, 2011 U.K. Plan Other foreign countries Equity securities		Dec. 31, 2012 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)	Dec. 31, 2011 U.K. Plan Quoted Prices in Active Markets for Identical Assets (Level 1) Real estate		Dec. 31, 2012 U.K. Plan Quoted Prices in Active Markets for Identical Assets (Level 1) Cash		Dec. 31, 2011 U.K. Plan Quoted Prices in Active Markets for Identical Assets (Level 1) Cash		Dec. 31, 2012 U.K. Plan Significant Observable Inputs (Level 2)	Dec. 31, 2011 U.K. Plan Significant Observable Inputs (Level 2)	Dec. 31, 2012 U.K. Plan Significant Observable Inputs (Level 2) Gobal return fund		Dec. 31, 2011 U.K. Plan Significant Observable Inputs (Level 2) Gobal return fund		Dec. 31, 2012 U.K. Plan Significant Observable Inputs (Level 2) Corporate bonds		Dec. 31, 2011 U.K. Plan Significant Observable Inputs (Level 2) Corporate bonds		Dec. 31, 2011 U.K. Plan Significant Observable Inputs (Level 2) Real estate		Dec. 31, 2012 U.K. Plan Significant Observable Inputs (Level 2) U.K Equity securities		Dec. 31, 2011 U.K. Plan Significant Observable Inputs (Level 2) U.K Equity securities		Dec. 31, 2012 U.K. Plan Significant Observable Inputs (Level 2) Other foreign countries Equity securities		Dec. 31, 2011 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, 2012 U.K. Plan Significant Unobservable Inputs (Level 3) Real estate	Dec. 31, 2011 U.K. Plan Significant Unobservable Inputs (Level 3) Real estate		Dec. 31, 2012 Canadian Plan	Dec. 31, 2011 Canadian Plan	Dec. 31, 2012 Canadian Plan Government bonds	Dec. 31, 2011 Canadian Plan Government bonds	Dec. 31, 2011 Canadian Plan Corporate bonds	Dec. 31, 2012 Canadian Plan Other short-term investment		Dec. 31, 2011 Canadian Plan Other short-term investment		Dec. 31, 2012 Canadian Plan Cash and cash equivalents		Dec. 31, 2011 Canadian Plan Cash and cash equivalents		Dec. 31, 2011 Canadian Plan Canada Equity securities		Dec. 31, 2012 Canadian Plan Canada Equity securities		Dec. 31, 2012 Canadian Plan Canada Corporate bonds	Dec. 31, 2011 Canadian Plan Other foreign countries Equity securities		Dec. 31, 2012 Canadian Plan Other foreign countries Equity securities		Dec. 31, 2012 Canadian Plan Other foreign countries Corporate bonds	Dec. 31, 2012 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)	Dec. 31, 2012 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) Government bonds	Dec. 31, 2011 Canadian Plan Quoted Prices in Active Markets for Identical Assets (Level 1) Corporate bonds	Dec. 31, 2012 Canadian Plan Quoted Prices in Active Markets for Identical Assets (Level 1) Other short-term investment		Dec. 31, 2012 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) Cash and cash equivalents		Dec. 31, 2012 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) Canada Equity securities		Dec. 31, 2012 Canadian Plan Quoted Prices in Active Markets for Identical Assets (Level 1) Canada Corporate bonds	Dec. 31, 2012 Canadian Plan Quoted Prices in Active Markets for Identical Assets (Level 1) Other foreign countries Equity securities		Dec. 31, 2011 Canadian Plan Quoted Prices in Active Markets for Identical Assets (Level 1) Other foreign countries Equity securities		Dec. 31, 2012 Canadian Plan Quoted Prices in Active Markets for Identical Assets (Level 1) Other foreign countries Corporate bonds	Dec. 31, 2012 Canadian Plan Significant Observable Inputs (Level 2)	Dec. 31, 2011 Canadian Plan Significant Observable Inputs (Level 2)	Dec. 31, 2012 Canadian Plan Significant Observable Inputs (Level 2) Government bonds	Dec. 31, 2012 Canadian Plan Significant Observable Inputs (Level 2) Other short-term investment		Dec. 31, 2011 Canadian Plan Significant Observable Inputs (Level 2) Other short-term investment		Dec. 31, 2012 Canadian Plan Significant Observable Inputs (Level 2) Canada Equity securities		Dec. 31, 2011 Canadian Plan Significant Observable Inputs (Level 2) Canada Equity securities		Dec. 31, 2012 Canadian Plan Significant Observable Inputs (Level 2) Canada Corporate bonds	Dec. 31, 2012 Canadian Plan Significant Observable Inputs (Level 2) Other foreign countries Equity securities		Dec. 31, 2011 Canadian Plan Significant Observable Inputs (Level 2) Other foreign countries Equity securities		Dec. 31, 2012 Canadian Plan Significant Observable Inputs (Level 2) Other foreign countries Corporate bonds
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	$ (260)
Net prior service cost	1,044
Net amount expected to be recognized	784
Target allocations of plan assets
Target allocation in debt securities (as a percent)				35.00%				10.00%
Target allocation in equities (as a percent)																			15.00%	20.00%																																																						20.00%					40.00%
Target allocation in real estate (as a percent)												5.00%												15.00%																																					40.00%
Total pension assets		$ 52,120	$ 42,538	$ 17,660	[1]	$ 15,386	[1]	$ 5,215	[1]	$ 4,243	[1]	$ 9,356	[1]	$ 10,431	$ 374	[2]	$ 171	[1]		$ 10,950	[1]	$ 7,056	[1]	$ 7,490	[1]	$ 6,326	[1]	$ 374	$ 171	$ 0	[1]	$ 374	[2]	$ 171	[1]	$ 41,315	$ 33,011	$ 17,660	[1]	$ 15,386	[1]	$ 5,215	[1]	$ 4,243	[1]	$ 0	[1]	$ 10,950	[1]	$ 7,056	[1]	$ 7,490	[1]	$ 6,326	[1]	$ 9,356	$ 2,416	$ 10,431	$ 9,356	[1]	$ 35,921	$ 30,658	$ 5,690	$ 4,629	$ 6,470	$ 839	[3]	$ 377	[3]	$ 240	[4]	$ 254	[4]	$ 9,759	[5]	$ 6,908	[5]	$ 6,778	$ 9,169	[5]	$ 15,348	[5]	$ 118	$ 23,335	$ 25,175	$ 0	$ 4,629	$ 6,470	$ 839	[3]	$ 240	[4]	$ 254	[4]	$ 6,908	[5]	$ 9,049	[5]	$ 0	$ 15,348	[5]	$ 4,773	[5]	$ 0	$ 12,586	$ 5,483	$ 5,690	$ 0	[3]	$ 377	[3]	$ 0	[5]	$ 710	[5]	$ 6,778	$ 0	[5]	$ 4,396	[5]	$ 118

[1] The assets are invested through managed funds that are valued using inputs derived principally from quoted prices in active markets for the underlying assets in the fund.

[2] The fair value of cash equals its book value.

[3] Other short-term investments are investments in pooled money market funds that are valued using inputs derived principally from the quoted prices in active markets for the underlying assets in the pool.

[4] The carrying value of cash and cash equivalents approximates fair value because of the short-term maturity of these instruments.

[5] Direct investments in equity securities are valued at quoted prices in active markets for identical assets. Equity securities invested through pooled funds are valued using inputs derived principally from the quoted prices in active markets for the underlying assets in the pool.