Debt - Additional Information (Details) - USD ($)				3 Months Ended			9 Months Ended
	Mar. 03, 2021	Oct. 29, 2020	Apr. 15, 2020	Sep. 30, 2021	Sep. 30, 2020	Jun. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2016
Debt Instrument [Line Items]
Loss on debt extinguishment				$ 0	$ 0		$ 0	$ 28,500,000
2027 Notes | Senior Notes
Debt Instrument [Line Items]
Aggregate principal amount		$ 485,000,000		$ 485,000,000.0			$ 485,000,000.0		$ 485,000,000.0
Interest rate (as a percent)		6.875%		6.875%			6.875%
Aggregate principal amount of convertible debt outstanding				$ 477,800,000			$ 477,800,000		476,900,000
2027 Notes | Senior Notes | Prior to November 1, 2023
Debt Instrument [Line Items]
Redemption price, percent of principal amount of notes redeemed (as a percent)		100.00%
Proportion of notes with option to redeem (as a percent)		40.00%
Redemption price, proportion of principal amount (as a percent)		106.875%
2027 Notes | Senior Notes | Change of Control
Debt Instrument [Line Items]
Redemption price, proportion of principal amount (as a percent)		101.00%
2022 Notes | Senior Notes
Debt Instrument [Line Items]
Interest rate (as a percent)			10.75%
Redemption price, percent of principal amount of notes redeemed (as a percent)			105.375%
Principal amount redeemed			$ 440,000,000
Repurchase amount			487,300,000
Call premium			23,650,000
Accrued interest			$ 23,650,000
Loss on debt extinguishment						$ 28,500,000
Premium						23,650,000
Write off of unamortized discount and fees related to issuance of the notes						$ 4,800,000
2021 Notes | Senior Notes
Debt Instrument [Line Items]
Aggregate principal amount									$ 84,200,000		$ 213,500,000
Interest rate (as a percent)				5.50%			5.50%		5.50%
Aggregate principal amount of convertible debt outstanding				$ 0			$ 0		$ 83,600,000	$ 84,200,000
Aggregate principal amount of debt converted	$ 84,200,000
Aggregate cash payments to note holders for debt conversion	86,500,000
Aggregate cash payment for outstanding principal	84,200,000
Aggregate cash payment for accrued interest	$ 2,300,000
Aggregate shares of common stock issued pursuant to debt conversion (in shares)	4,537,123
Amount of conversion, shares received upon exercise of capped call transactions (in shares)	1,251,460
Amount of conversion, increase in outstanding common stock (in shares)	3,285,663
Installment Payment Agreement
Debt Instrument [Line Items]
Aggregate principal amount										$ 27,700,000
Interest rate (as a percent)										7.00%
Amount reported in current maturities of long-term debt				5,900,000			5,900,000
Software Licenses Financing Agreement
Debt Instrument [Line Items]
Aggregate principal amount										$ 19,300,000
Interest rate (as a percent)										5.47%
Amount reported in current maturities of long-term debt				3,800,000			3,800,000
Amended and Restated ABL Credit Facility | Revolving Credit Facility
Debt Instrument [Line Items]
Maximum borrowing capacity		$ 145,000,000
Accordion feature increase limit		$ 175,000,000
Borrowings outstanding				0			0
Availability under the facility, net of letters of credit issued				75,100,000			75,100,000
Springing maturity, period prior to any date on which domestic pension contributions in an amount in excess of threshold are required to be paid		91 days
Springing maturity, date on which pension contributions to pension funds in the United States are required to be paid, threshold excess amount		$ 100,000,000
Springing maturity, conditions, minimum liquidity		130,000,000
Amended and Restated ABL Credit Facility | Letter of Credit
Debt Instrument [Line Items]
Maximum borrowing capacity		$ 40,000,000
Letters of credit outstanding				$ 5,700,000			$ 5,700,000
Amended and Restated ABL Credit Facility | Line of Credit | Revolving Credit Facility
Debt Instrument [Line Items]
Requirement to maintain minimum fixed charge coverage ratio (as a percent)		10.00%
Requirement to maintain minimum fixed charge coverage ratio, availability threshold		$ 14,500,000
Amount of aggregate default under other debt that would trigger event of default		$ 50,000,000