Employee Benefit Plans - Additional Information (Details) - USD ($)	3 Months Ended			6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Mar. 31, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Supplemental executive retirement plan	$ 11,050,000			$ 11,050,000		$ 10,197,000
Foreign Pension Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined benefit plan arrangement minimum age				60 years
Completed at least credited service period				5 years
Defined benefit plan assumptions used calculating benefit obligation benefits payable per service year				one-half month’s salary for each year of credited service
Net periodic benefit cost	66,000	$ 67,000		$ 132,000	$ 131,000
Accumulated postretirement benefit obligation	1,800,000			1,800,000		1,600,000
Employer contributions to benefit plans				$ 0
Supplemental Executive Retirement Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined benefit plan arrangement minimum age				55 years
Completed at least credited service period				10 years
Net periodic benefit cost	426,000	364,000		$ 852,000	729,000
Employer contributions to benefit plans				$ 0
Normal retirement age				65 years
Early retirement age				55 years
Vesting percentage under the plan for attaining age 55 and 10 years of service				100.00%
Vesting percentage under the plan prior to attaining age 55 and 10 years of service				0.00%
Defined benefit plan employees minimum requisition period under specific conditions				5 years
Benefits payable targeted percentage				45.00%
Period in which the executive officer earned the highest salary and bonus				3 years
Employment period for computation of benefit				10 years
Eligible age under condition one for reduced benefits under the plan				62 years
Eligible service under condition one for reduced benefits under plan				10 years
Eligible age under condition two for reduced benefits under plan				55 years
Eligible service under condition two for reduced benefits under plan				25 years
Lump sum payment period				10 years
Supplemental executive retirement plan	11,100,000			$ 11,100,000		10,200,000
Supplemental Executive Retirement Health Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Net periodic benefit cost		$ 84,000			$ 46,000
Accumulated postretirement benefit obligation	$ 0			$ 0		$ 0
Lump-sum payment to the participant in SERHP			$ 600,000
Settlement gain (loss)			$ 100,000