Property and Equipment - Components of Property and Equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Property, Plant and Equipment [Abstract]
Aircraft	$ 19,063	$ 18,270
Equipment	20,044	18,932
Furniture and fixtures	7,248	7,232
Leasehold improvements	21,945	24,392
Property, plant and equipment, gross	68,300	68,826
Accumulated depreciation and amortization	(58,517)	(58,491)
Total property and equipment, net	$ 9,783	$ 10,335