Retirement Plans (Details) - Projected benefit obligation and plan assets (Defined benefit plan, USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Defined benefit plan
Change in projected benefit obligation:
Projected benefit obligation, beginning of year	$ 72,267	$ 66,327
Service cost	1,291	919
Interest cost	3,557	3,393
Actuarial (gain) loss	7,922	3,837
Benefits and expenses paid	(2,069)	(1,612)
Foreign currency (gains) losses	1,086	(597)
Settlements	(971)	0
Projected benefit obligation, end of year	83,083	72,267
Change in plan assets:
Fair value of plan assets - beginning of year	34,955	33,294
Actual return on plan assets	3,101	969
Employer contributions	2,133	1,941
Benefits and expenses paid	(1,258)	(1,132)
Foreign currency (gains) losses	381	(117)
Fair value of plan assets - end of year	39,313	34,955
Funded status - end of year	(43,770)	(37,312)
Accrued pension liability	$ 43,770	$ 37,312