Derivatives - Interest Rate Swaps (Details) - USD ($)		1 Months Ended	12 Months Ended
		Dec. 31, 2020	Dec. 31, 2020	Dec. 31, 2019		Dec. 31, 2018	Apr. 30, 2019
Derivatives
Derivative, notional amount		$ 350,000,000.0	$ 350,000,000.0				$ 850,000,000.0
Derivative, fixed interest rate							2.27825%
Derivative, termination payment		10,900,000
Derivative, amount terminated		500,000,000.0	500,000,000.0
Derivative liability outstanding		10,900,000	10,900,000
Cash flow hedge gain (loss) amortized into interest rate expense			14,500,000	$ 400,000
Income tax benefit			1,300,000	3,400,000
Loss on designated cash flow hedge	[1]		(4,300,000)	(9,000,000.0)	[2],[3]	$ 0
Cash flow hedge gain (loss) amortized into interest rate expense in the next 12 months		18,200,000	18,200,000
Fair value of derivative assets—long-term		(37,100,000)	(37,100,000)	(14,400,000)
Derivative liability, noncurrent		(2,500,000)	(2,500,000)	(6,800,000)
Interest rate swaps
Derivatives
Change in fair value of derivatives			(5,600,000)	(12,400,000)
Fair value of derivative assets—long-term		(7,600,000)	(7,600,000)	(5,600,000)
Derivative liability, noncurrent		0	0	(6,800,000)
Net fair value of commodity swaps		$ (7,600,000)	$ (7,600,000)	$ (12,400,000)

[1] The loss on designated cash flow hedge recorded in accumulated other comprehensive loss for the years ended December 31, 2020 and 2019 was net of a tax benefit of $1.3 million and $3.4 million, respectively

[2] Includes a tax benefit of $1.3 million.

[3] Includes a tax benefit of $3.4 million.