Property and Equipment - Components of Property and Equipment (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Property, Plant and Equipment [Abstract]
Aircraft	$ 18,154	$ 17,844
Equipment	18,516	18,175
Furniture and fixtures	7,335	7,578
Leasehold improvements	24,446	25,567
Property, plant and equipment, gross	68,451	69,164
Less accumulated depreciation and amortization	(56,951)	(54,760)
Total property and equipment, net	$ 11,500	$ 14,404