Borrowings - Schedule of Line of Credit Facility Debt and Key Terms (Detail) - USD ($) $ / shares in Units, $ in Millions		9 Months Ended
		Sep. 30, 2021		Mar. 04, 2021	Dec. 31, 2020	Apr. 10, 2020
Debt Instrument [Line Items]
Amount Due		$ 288.4
Senior Convertible Notes
Debt Instrument [Line Items]
Amount Due		$ 230.0
Annual interest rate		2.50%
Maturity date		2026-03
Conversion price		$ 5.21		$ 5.21
MidCap Credit Facility
Debt Instrument [Line Items]
Amount Due	[1]	$ 40.0			$ 50.0
Maturity date	[1]	2025-08
MidCap Credit Facility | LIBOR
Debt Instrument [Line Items]
Annual interest rate	[1]	6.25%
Interest rate floor	[1]	1.00%
5.75% 2024 Convertible Note
Debt Instrument [Line Items]
Amount Due	[2]				5.0
Annual interest rate	[2]	5.75%
Maturity date	[2]	2024-11
Conversion price	[2]	$ 3.00
PPP Loan
Debt Instrument [Line Items]
Amount Due	[3]				4.9
Annual interest rate		0.98%	[3]			0.98%
Maturity date	[3]	2022-04
Mann Group | Convertible Promissory Note
Debt Instrument [Line Items]
Amount Due		$ 18.4			28.0
Accrued interest paid-in-kind		$ 0.3			0.6
Annual interest rate	[4]	2.50%
Maturity date	[4]	2025-12
Conversion price		$ 2.50
Mann Group | Non Convertible Promissory Note
Debt Instrument [Line Items]
Amount Due					35.1
Accrued interest paid-in-kind					$ 3.6
Annual interest rate		7.00%
Maturity date		2024-11

[1] In April 2021, the Company prepaid $10.0 million principal balance and amended the MidCap credit facility. The interest rate prior to the amendment was one-month LIBOR (2% floor) plus 6.75% and the maturity date was in August 2024

[2] In February 2021, the $5.0 million principal balance was converted into 1,666,667 shares of the Company’s common stock

[3] In July 2021, the Company received full forgiveness from the SBA for the $4.9 million principal balance of the PPP loan and recognized a gain on extinguishment of debt for the full principal balance and a de minimis amount of accrued but unpaid interest

[4] In April 2021, the Mann Group convertible note was amended. The interest rate prior to the amendment was 7.00% and the maturity date was in November 2024