Property and Equipment - Narrative (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Property Plant And Equipment [Abstract]
Depreciation expense	$ 12.5	$ 10.0	$ 32.9	$ 25.1
Non-cash increases property and equipment acquired under capital leases			1.1	1.0
Non-cash increases property and equipment purchases in accounts payable and accrued liabilities			$ 0.8	$ 5.6