Debt and Financing Obligation - Revolving Facility Narrative (Details) - USD ($)	Mar. 31, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
Outstanding balance	$ 944,500,000	$ 800,500,000
Revolving credit facility, due 2024 (Revolving Facility) | Line of Credit | Revolving Credit Facility
Debt Instrument [Line Items]
Maximum borrowing capacity	400,000,000.0
Letters of credit outstanding under revolving facility	11,800,000
Outstanding balance	300,000,000.0	$ 143,300,000
Remaining borrowing capacity	88,200,000
Revolving credit facility, due 2024 (Revolving Facility) | Line of Credit | Letter of Credit
Debt Instrument [Line Items]
Outstanding balance	$ 11,500,000