Retirement and Benefit Plans - (Details) (USD $)	12 Months Ended
	Dec. 31, 2014 Times Participants	Dec. 31, 2013	Dec. 31, 2012
Compensation and Retirement Disclosure [Abstract]
Company matching employee contributions	66.70%
Maximum percentage of matching contribution for total compensation	3.00%
Discretionary contributions, percentage of qualified wages	1.00%
Contribution expense	$ 2,698,000	$ 3,126,000	$ 3,620,000
Defined Benefit Plan Disclosure [Line Items]
Number of participants unaffected by plan conversion	3
Death benefit only plan, benefit payment as multiplier of final earnings	1
Net periodic benefit (income) costs	1,127,000
Death benefit only plan, benefit payment as multiplier of final earnings, current employee	3
Proceeds from life insurance policies	21,338,000
Accumulated other comprehensive income (loss)	7,601,000	5,414,000
Accumulated other comprehensive income, net change	2,187,000
Supplemental Executive Retirement Plan
Defined Benefit Plan Disclosure [Line Items]
Interest credited for active participants (as a percent)	0.00%
Accumulated benefit obligation	27,584,000	27,440,000
Assumption, future salary increase rate	4.00%
Assumed discount rate	3.95%	4.95%
Retirement age	67
Projected benefit obligation	27,584,000	27,440,000
Interest (benefit) cost	377,000	(236,000)	187,000
Net periodic benefit (income) costs	539,000	(14,000)	370,000
Benefit payments	394,000	398,000	398,000
Death Benefit Only Plan
Defined Benefit Plan Disclosure [Line Items]
Net periodic benefit (income) costs	808,000	(259,000)	509,000
Service cost and accrual adjustments	692,000	(364,000)	412,000
Switzerland | Foreign Postretirement Benefit Plan
Defined Benefit Plan Disclosure [Line Items]
Number of plans	2
Netherlands | Foreign Postretirement Benefit Plan
Defined Benefit Plan Disclosure [Line Items]
Retirement age	65
Europe | Foreign Postretirement Benefit Plan
Defined Benefit Plan Disclosure [Line Items]
Amounts recognized in other comprehensive income (loss)	$ 220,000	$ 205,000	$ 105,000