Property and Equipment - Summary of Property and Equipment Net (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Property Plant And Equipment [Line Items]
Property and Equipment, Estimated Useful Lives	30 years
Property, gross	$ 41,348	$ 34,789
Less: Accumulated depreciation and amortization	(18,149)	(12,181)
Property and equipment, net, excluding Build-to-suit assets	23,199	22,608
Build-to-suit lease asset under construction		25,560
Property and equipment, net	23,199	48,168
Vehicles Acquired Under Capital Leases
Property Plant And Equipment [Line Items]
Property, gross	$ 20,384	24,149
Furniture and Computer and Other Equipment
Property Plant And Equipment [Line Items]
Property and Equipment, Estimated Useful Lives	3 years
Property, gross	$ 6,270	6,524
Leasehold Improvements
Property Plant And Equipment [Line Items]
Property, gross	$ 14,694	$ 4,116
Minimum | Vehicles Acquired Under Capital Leases
Property Plant And Equipment [Line Items]
Property and Equipment, Estimated Useful Lives	3 years
Minimum | Leasehold Improvements
Property Plant And Equipment [Line Items]
Property and Equipment, Estimated Useful Lives	1 year
Maximum | Vehicles Acquired Under Capital Leases
Property Plant And Equipment [Line Items]
Property and Equipment, Estimated Useful Lives	4 years
Maximum | Leasehold Improvements
Property Plant And Equipment [Line Items]
Property and Equipment, Estimated Useful Lives	12 years