Net Periodic Benefit Cost-Defined Benefit Plans (Details) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Dec. 31, 2012
Net periodic benefit cost of the domestic non-contributory defined benefit plan
Service cost	$ 159,000	$ 156,000	$ 318,000	$ 313,000
Interest cost	193,000	186,000	386,000	372,000
Expected return on plan assets	(246,000)	(195,000)	(492,000)	(391,000)
Amortization of transition obligation				(1,000)
Amortization of prior service cost	6,000	6,000	13,000	13,000
Amortization of net loss	120,000	109,000	239,000	218,000
Net periodic cost	232,000	262,000	464,000	524,000
Minimum additional contributions anticipated during the remainder of 2013	175,000		175,000
Expected contribution to Pension Plan in 2013					400,000
Employer contributions made to the defined benefit plan			$ 430,000