Significant Customers (Details) (USD $) In Thousands, unless otherwise specified			3 Months Ended		6 Months Ended				3 Months Ended		6 Months Ended
	Jun. 30, 2014	Dec. 31, 2013	Jun. 30, 2014 DHL [Member] Revenues from Leases and Contracted Services [Member] Customer Concentration Risk [Member]	Jun. 30, 2013 DHL [Member] Revenues from Leases and Contracted Services [Member] Customer Concentration Risk [Member]	Jun. 30, 2014 DHL [Member] Revenues from Leases and Contracted Services [Member] Customer Concentration Risk [Member]	Jun. 30, 2013 DHL [Member] Revenues from Leases and Contracted Services [Member] Customer Concentration Risk [Member]	Jun. 30, 2014 DHL [Member] Accounts Receivable [Member]	Dec. 31, 2013 DHL [Member] Accounts Receivable [Member]	Jun. 30, 2014 US Military [Member] Revenues from Services Performed [Member] Customer Concentration Risk [Member]	Jun. 30, 2013 US Military [Member] Revenues from Services Performed [Member] Customer Concentration Risk [Member]	Jun. 30, 2014 US Military [Member] Revenues from Services Performed [Member] Customer Concentration Risk [Member]	Jun. 30, 2013 US Military [Member] Revenues from Services Performed [Member] Customer Concentration Risk [Member]	Jun. 30, 2014 US Military [Member] Accounts Receivable [Member]	Dec. 31, 2013 US Military [Member] Accounts Receivable [Member]
Concentration Risk [Line Items]
Percentage of consolidated revenues			57.00%	56.00%	57.00%	54.00%			17.00%	16.00%	16.00%	17.00%
Accounts receivable	$ 57,126	$ 52,247					$ 32,400	$ 24,100					$ 6,100	$ 4,800