Property and Equipment - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Property, Plant and Equipment [Line Items]
Property and equipment, net	$ 57,436	$ 65,664
Accumulated depreciation	100,354	97,250
Property and equipment, gross	157,790	162,914
Depreciation and amortization	10,600	14,000	$ 20,100
Aircraft And Aircraft-Related Equipment
Property, Plant and Equipment [Line Items]
Property and equipment, net	38,400	40,000
Accumulated depreciation	10,200	8,600
Computer Equipment And Purchased Software
Property, Plant and Equipment [Line Items]
Property and equipment, gross	60,692	64,615
Computer Equipment And Purchased Software | Assets Held under Capital Leases
Property, Plant and Equipment [Line Items]
Accumulated depreciation	2,200	2,300
Property and equipment, gross	$ 2,200	$ 2,400