Property and Equipment - Narrative (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Property Plant And Equipment [Abstract]
Depreciation expense	$ 11.3	$ 8.4	$ 20.4	$ 15.1
Non-cash increases property and equipment acquired under capital leases			0.8	0.7
Non-cash increases property and equipment purchases in accounts payable and accrued liabilities			$ 2.0	$ 2.7