Pension and Other Post-Retirement Plans (Details) (USD $)	3 Months Ended		9 Months Ended		6 Months Ended	9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	Jun. 30, 2012 U.K.-based union employees, U.K. Plan Year	Sep. 30, 2012 Maximum
Defined benefit plan disclosure
Number of years of employee's average compensation preceding retirement (in years)					2
Decrease in pension benefit obligation			$ 5,825,000
Rate of compensation increase						2.00%
Components of net periodic pension benefit cost
Service cost	428,000	589,000	1,564,000	1,512,000
Interest cost	1,135,000	1,114,000	3,429,000	3,461,000
Expected return on plan assets	(1,436,000)	(1,161,000)	(3,890,000)	(3,485,000)
Amortization of actuarial gains	135,000	95,000	637,000	284,000
Amortization of prior service costs	(113,000)	(54,000)	(151,000)	(59,000)
Net periodic cost	149,000	583,000	1,589,000	1,713,000
Employer's matching contribution on the dollar for the first 6 percent of participant contributions, effective January 1, 2010			$ 0.375
Maximum percentage of participant contributions eligible for Employer contribution match, towards defined contribution plan (as a percent)			6.00%
Percentage of employer's contribution under 401(k) plan matching up to 6 percent of participant contributions subject to maximum percentage of eligible compensation, effective from January 1, 2010 (as a percent)			2.25%