Pensions (Details) (USD $)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012
Multi-Employer Plan
Liability under multi-employer plan	$ 600,000		$ 600,000		$ 1,700,000
U.S. Plans
Components of net periodic pension costs of the plans
Service cost	291,000	265,000	874,000	795,000
Interest cost	975,000	1,189,000	3,229,000	3,569,000
Expected return on plan assets	(1,661,000)	(1,539,000)	(4,995,000)	(4,620,000)
Amortization of prior service cost	18,000	7,000	56,000	20,000
Net actuarial loss amortization	909,000	854,000	2,727,000	2,564,000
Net periodic pension cost	532,000	776,000	1,891,000	2,328,000
Expected long-term rate of return on plan assets (as a percent)			7.75%
Employer contributions, 2013					1,300,000
Employer actual contribution of prior year end expected future contribution			1,300,000
Additional employer contributions			1,200,000
European Plans
Components of net periodic pension costs of the plans
Service cost	80,000	42,000	237,000	126,000
Interest cost	390,000	439,000	1,146,000	1,317,000
Expected return on plan assets	(326,000)	(325,000)	(957,000)	(975,000)
Net actuarial loss amortization	53,000	4,000	155,000	12,000
Foreign currency translation	4,000	(6,000)	12,000	(7,000)
Net periodic pension cost	201,000	154,000	593,000	473,000
Employer contributions, 2013					2,100,000
Employer contributions			1,100,000
Expected employer contribution to pension plans over the balance of current year	$ 1,000,000		$ 1,000,000
European Plans | Minimum
Components of net periodic pension costs of the plans
Expected long-term rate of return on plan assets (as a percent)			4.50%
European Plans | Maximum
Components of net periodic pension costs of the plans
Expected long-term rate of return on plan assets (as a percent)			5.40%