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Background and Basis of Presentation - Additional Information (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Jun. 30, 2021	Jan. 01, 2021	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Dec. 31, 2019
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Accrued liabilities	$ 73,320			$ 68,565
Equity	1,354,517	$ 1,337,882		609,635	$ 645,392	$ 498,378	$ 498,829
Additional Paid-In Capital
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Equity	1,717,421	1,706,855		1,030,577	1,092,574	907,908	916,095
Accumulated Deficit
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Equity	$ (361,497)	$ (368,148)		(422,601)	$ (448,644)	$ (411,504)	(416,292)
Cumulative Effect, Period of Adoption, Adjustment
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Equity				(378,138)			(88)
Cumulative Effect, Period of Adoption, Adjustment \| Additional Paid-In Capital
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Equity				(465,006)
Cumulative Effect, Period of Adoption, Adjustment \| Accumulated Deficit
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Equity				86,868			$ (88)
Cumulative Effect, Period of Adoption, Adjustment \| Accounting Standards Update 2020-06 \| Additional Paid-In Capital
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Equity			$ (465,000)
Cumulative Effect, Period of Adoption, Adjustment \| Accounting Standards Update 2020-06 \| Accumulated Deficit
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Equity			86,900
Cumulative Effect, Period of Adoption, Adjustment \| Accounting Standards Update 2020-06 \| Senior Notes
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Equity			$ 378,100
Revision of Prior Period, Reclassification, Adjustment
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Current operating lease liabilities				(6,600)
Accrued liabilities				$ 6,600