Revenues - (Details) - USD ($)	6 Months Ended
	Jun. 30, 2019	Dec. 31, 2018
Revenue from Contract with Customer [Abstract]
Contract with customer, asset	$ 0	$ 0
Deferred revenues	564,500,000	$ 385,100,000
Increase in contract liabilities	179,400,000
Billings paid in advance	376,900,000
Revenue recognized	197,500,000
Revenue, remaining performance obligation	$ 564,500,000
Revenue, remaining performance obligation, current, percentage	99.00%