Debt and Other Obligations - Seller Notes and the Deferred Payment Obligation (Details) - USD ($) $ in Millions	9 Months Ended
Sep. 30, 2021	Dec. 31, 2020
Seller Notes
Debt and Other Obligations
Unamortized discount	$ 0.8	$ 0.9
Seller Notes \| Minimum
Debt and Other Obligations
Stated interest rates (as a percent)	2.50%
Seller Notes \| Maximum
Debt and Other Obligations
Stated interest rates (as a percent)	3.00%
Deferred payment obligation
Debt and Other Obligations
Unamortized discount	$ 0.4	$ 0.5
Stated interest rates (as a percent)	3.00%
Annual installment payment period	3 years

Amount, after accumulated amortization, of debt discount.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 1A
-URI http://asc.fasb.org/extlink&oid=124435984&loc=d3e28541-108399

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=114775985&loc=d3e28878-108400

Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 1D
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=123466505&loc=SL123495340-112611

Name:	us-gaap_DebtInstrumentUnamortizedDiscount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant