Revenues Performance Obligations (Details) $ in Millions	9 Months Ended
	Sep. 30, 2020 USD ($)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Fixed Fee Revenues Recognized	$ 816.9
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-10-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	3 months	[1]
Estimated revenues from contracts with customers from unsatisfied performance obligations as of September 30, 2020	$ 295.5	[1]
Operating revenues which are fixed and determinable (operating leases)	5.5	[1]
Total projected operating revenues under committed firm agreements as of September 30, 2020	$ 301.0	[1]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	1 year
Estimated revenues from contracts with customers from unsatisfied performance obligations as of September 30, 2020	$ 1,077.0
Operating revenues which are fixed and determinable (operating leases)	23.0
Total projected operating revenues under committed firm agreements as of September 30, 2020	$ 1,100.0
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	21 years
Estimated revenues from contracts with customers from unsatisfied performance obligations as of September 30, 2020	$ 7,534.5
Operating revenues which are fixed and determinable (operating leases)	220.0
Total projected operating revenues under committed firm agreements as of September 30, 2020	7,754.5
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: (nil)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Estimated revenues from contracts with customers from unsatisfied performance obligations as of September 30, 2020	8,907.0
Operating revenues which are fixed and determinable (operating leases)	248.5
Total projected operating revenues under committed firm agreements as of September 30, 2020	$ 9,155.5

[1] The 2020 period is for the three months ending December 31, 2020. For the nine months ended September 30, 2020, the Company recognized $816.9 million of fixed fee revenues for the fulfillment of performance obligations.