Commitments and Contingencies - Additional Information (Details) - USD ($)	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Commitments and Contingencies [Line Items]
Maintenance contracts with equipment vendors, expiration year	2021
Equipment maintenance contract payments	$ 11,100,000	$ 10,300,000
Liability related to guarantees and indemnities	$ 0
Minimum
Commitments and Contingencies [Line Items]
Period since inception of equipment maintenance contract	1 year
Maximum
Commitments and Contingencies [Line Items]
Period since inception of equipment maintenance contract	5 years
Equipment Purchase Commitments
Commitments and Contingencies [Line Items]
Equipment purchase commitment	$ 15,200,000