Debt and Financing Obligation - Schedule of Debt (Details) - USD ($)	Sep. 30, 2021	Jun. 22, 2021	Dec. 31, 2020
Debt Instrument [Line Items]
Total borrowings	$ 614,700,000		$ 690,500,000
Original issue discount	0		(3,300,000)
Debt issuance costs	(13,800,000)		(10,300,000)
Total debt and financing obligation	600,900,000		676,900,000
Less: current portion of financing obligation	3,100,000		3,000,000.0
Long-term debt and financing obligation	$ 597,800,000		673,900,000
Line of Credit | Revolving Credit Facility
Debt Instrument [Line Items]
Maximum borrowing capacity		$ 350,000,000
4.875 percent senior notes, due 2029 ("2029 Senior Notes") | Senior notes
Debt Instrument [Line Items]
Interest rate on senior notes (as a percent)	4.875%	487.50%
Total borrowings	$ 500,000,000.0		0
7.500 percent senior notes, due 2025 ("2025 Senior Notes") | Senior notes
Debt Instrument [Line Items]
Interest rate on senior notes (as a percent)	7.50%
Total borrowings	$ 0		587,300,000
$350.0 million revolving credit facility, due 2026 ("Revolving Facility") | Line of Credit | Revolving Credit Facility
Debt Instrument [Line Items]
Maximum borrowing capacity	350,000,000
Total borrowings	$ 102,000,000.0		88,300,000
5.346 percent financing obligation, due 2024 | Financing Obligation
Debt Instrument [Line Items]
Interest rate on senior notes (as a percent)	5.346%
Total borrowings	$ 12,700,000		$ 14,900,000