Debt (Details) - Long-term Debt, Type [Domain] - USD ($)	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Line of Credit Facility [Line Items]
Debt issuance cost	$ 100,000	$ 200,000
Insurance Premium Financed [Member] | UNITED STATES
Line of Credit Facility [Line Items]
Other Short-term Borrowings	1,000,000
Domestic Line of Credit [Member] | Letter of Credit [Member] | UNITED STATES
Line of Credit Facility [Line Items]
Outstanding letters of credit	6,200,000		$ 6,400,000
Pnc Bank [Member] | Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Remaining borrowing capacity	3,600,000
Pnc Bank [Member] | Revolving Credit Facility [Member] | UNITED STATES
Line of Credit Facility [Line Items]
Revolving line of credit maximum borrowing capacity	34,000,000.0
Pnc Bank [Member] | Letter of Credit [Member] | UNITED STATES
Line of Credit Facility [Line Items]
Revolving line of credit maximum borrowing capacity	$ 10,000,000.0
Revolving Credit and Security Agreement expiring date	Dec. 11, 2018
Pnc Bank [Member] | Secured Debt [Member] | UNITED STATES
Line of Credit Facility [Line Items]
Revolving line of credit maximum borrowing capacity	$ 15,000,000
Long-term Debt	$ 6,800,000