Property and Equipment - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Property Plant And Equipment [Abstract]
Amortization of leased assets	$ 2.9	$ 1.9	$ 1.3
Property and equipment acquired under capital leases	$ 2.7	$ 3.5