Pensions (Details) (USD $)	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012
Multi-Employer Plan
Liability under multi-employer plan	$ 1,600,000		$ 1,600,000
U.S. Plans
Components of net periodic pension costs of the plans
Service cost	291,000	265,000
Interest cost	1,127,000	1,216,000
Expected return on plan assets	(1,667,000)	(1,559,000)
Amortization of prior service cost	19,000	19,000
Net actuarial (gain) loss amortization	909,000	834,000
Net periodic pension cost	679,000	775,000
Expected long-term rate of return on plan assets (as a percent)	7.75%
Employer contributions, 2013			1,300,000
Employer contributions	100,000
Expected employer contribution to pension plans over the balance of current year	1,200,000
European Plans
Components of net periodic pension costs of the plans
Service cost	78,000	42,000
Interest cost	374,000	439,000
Expected return on plan assets	(237,000)	(325,000)
Net actuarial (gain) loss amortization	(24,000)	4,000
Foreign currency translation	6,000	1,000
Net periodic pension cost	197,000	161,000
Employer contributions, 2013			2,100,000
Employer contributions	400,000
Expected employer contribution to pension plans over the balance of current year	$ 1,700,000
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%