Fair Value of Financial Instruments (Details) (USD $)	Dec. 31, 2012	Dec. 31, 2011
Assets and liabilities measured at fair value [Abstract]
Standby letters of credit and surety bonds	$ 6,000,000
Number of standby letters of credit	14
Number of surety bonds	5
Number of bid bonds contract	15
Number of stand by letters of credit deposited in certificates of deposit	6
Restricted cash and investments	1,800,000
Number of additional letters of credit collateralized using the line of credit	7
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Assets and liabilities measured at fair value [Abstract]
Money market fund	18,082,000	8,163,000
Certificate of deposit	890,000	5,976,000
Foreign exchange contracts - Assets	0	0
Total assets	18,972,000	14,139,000
Foreign exchange contracts - Liabilities	0	0
Total liabilities	0	0
Significant Other Observable Inputs (Level 2) [Member]
Assets and liabilities measured at fair value [Abstract]
Money market fund	0	0
Certificate of deposit	0	0
Foreign exchange contracts - Assets	316,000	483,000
Total assets	316,000	483,000
Foreign exchange contracts - Liabilities	(339,000)	(314,000)
Total liabilities	(339,000)	(314,000)
Significant Unobservable Inputs (Level 3) [Member]
Assets and liabilities measured at fair value [Abstract]
Money market fund	0	0
Certificate of deposit	0	0
Foreign exchange contracts - Assets	0	0
Total assets	0	0
Foreign exchange contracts - Liabilities	0	0
Total liabilities	$ 0	$ 0