Stockholders' Equity - Narrative (Details)						2 Months Ended	3 Months Ended	9 Months Ended
	Oct. 29, 2021 USD ($) $ / shares	Oct. 15, 2021 USD ($) shares	Sep. 22, 2021 USD ($) $ / shares shares	Sep. 17, 2021 tranche shares	Dec. 24, 2020 tranche shares	Apr. 09, 2021 USD ($)	Sep. 30, 2021 USD ($) $ / shares shares	Sep. 30, 2021 USD ($) payment $ / shares shares	Sep. 30, 2020 USD ($)	May 28, 2021 USD ($)	Dec. 31, 2020 USD ($) $ / shares	Dec. 23, 2020 $ / shares
Class of Stock [Line Items]
Share price (usd per share) | $ / shares			$ 5.81				$ 5.83	$ 5.83				$ 7.68
Proceeds from issuance of common and preferred stock								$ 22,640,000	$ 0
Preferred Stock, par value (usd per share) | $ / shares							$ 0.001	$ 0.001			$ 0.001
Aggregate principal amount exchanged							$ 46,000,000
Unsecured obligations | 2.50% Convertible notes due 2023
Class of Stock [Line Items]
Outstanding principal							(125,500,000)	$ (125,500,000)			$ (171,500,000)
Shares issued (shares) | shares								0
Notes exchanged			$ 34,500,000				34,500,000	$ 34,500,000
Aggregate principal amount exchanged							$ 46,000,000
Subsequent event
Class of Stock [Line Items]
Shares issued (shares) | shares		657,256
Notes exchanged		$ 5,000,000
Subsequent event | Unsecured obligations | 2.50% Convertible notes due 2023
Class of Stock [Line Items]
Aggregate principal amount exchanged		$ 5,000,000
Series A Preferred Stock
Class of Stock [Line Items]
Dividend rate (usd per share) | $ / shares			$ 0.25
Convertible Preferred Stock Converted to Other Securities								1
Common stock
Class of Stock [Line Items]
Shares issued (shares) | shares							5,945,718
September 2021 Securities Purchase Agreement | Series A Preferred Stock
Class of Stock [Line Items]
Preferred Stock, par value (usd per share) | $ / shares			0.001
At-The-Market Equity Sales Agreement
Class of Stock [Line Items]
Aggregate offering price (of up)										$ 50,000,000
Commission percentage										3.00%
Aggregate gross proceeds							$ 0	$ 800,000
Sale of stock (shares) | shares								92,497
Share price (usd per share) | $ / shares							$ 8.80	$ 8.80
Affiliated Entity
Class of Stock [Line Items]
Share price (usd per share) | $ / shares			$ 5.81
Affiliated Entity | December 2020 Securities Purchase Agreement
Class of Stock [Line Items]
Agreement to purchase shares (in shares) | shares							32,000,000	32,000,000
Number of tranches | tranche					3
Proceeds from issuance of common and preferred stock						$ 21,300,000		$ 500,000
Affiliated Entity | December 2020 Securities Purchase Agreement | Original Purchasers
Class of Stock [Line Items]
Agreement to purchase shares (in shares) | shares					4,166,663
Non-affiliate related entities | payment								3
Affiliated Entity | December 2020 Securities Purchase Agreement | Schuler Trust
Class of Stock [Line Items]
Agreement to purchase shares (in shares) | shares							3,964,843	3,964,843
Aggregate purchase price							$ 30,500,000	$ 30,500,000
Affiliated Entity | Rescission Agreement
Class of Stock [Line Items]
Agreement to purchase shares (in shares) | shares				2,643,228
Affiliated Entity | December 2020 Securities Purchase Agreement including Rescission Agreement
Class of Stock [Line Items]
Sale of stock (shares) | shares								201,820
Proceeds from issuance of common and preferred stock								$ 1,500,000
Affiliated Entity | September 2021 Securities Purchase Agreement
Class of Stock [Line Items]
Number of tranches | tranche				2
Affiliated Entity | September 2021 Securities Purchase Agreement | Subsequent event
Class of Stock [Line Items]
Aggregate proceeds	$ 10,200,000
Affiliated Entity | September 2021 Securities Purchase Agreement | Series A Preferred Stock
Class of Stock [Line Items]
Sale of stock (shares) | shares			2,636,364
Agreement to purchase preferred shares (in shares) | shares			3,954,546				1,318,182	1,318,182
Aggregate proceeds							$ 20,300,000
Affiliated Entity | September 2021 Securities Purchase Agreement | Series A Preferred Stock | Subsequent event
Class of Stock [Line Items]
Share price (usd per share) | $ / shares	$ 7.70
Aggregate purchase price	$ 30,500,000