Annual report pursuant to Section 13 and 15(d)

Stockholders' Equity - Interstate Agreement (Details)

Stockholders' Equity - Interstate Agreement (Details) - USD ($)				3 Months Ended								12 Months Ended
	Jan. 24, 2019	May 24, 2016	May 18, 2016	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Class of Stock [Line Items]
Convertible note payable				$ 0				$ 5,000,000				$ 0	$ 5,000,000
General and administrative expense				$ 5,856,000	$ 5,107,000	$ 4,335,000	$ 4,016,000	$ 6,352,000	$ 2,174,000	$ 3,913,000	$ 1,775,000	19,314,000	14,214,000	$ 600,000
Amortization of debt discount												$ 0	2,006,000
Warrant shares issued (in shares)				807,436								807,436
Ownership percentage of common stock upon conversion of convertible notes				8.30%								8.30%
Proceeds from issuance of common stock, net of transaction costs												$ 29,380,000	$ 28,753,000
Share price (in dollars per share)		$ 11.39
Interstate Battery System International, Inc.
Class of Stock [Line Items]
Allocated value		$ 10,000,000.0
Interstate Battery System International, Inc. \| Merrill Lynch US High Yield CCC Rate
Class of Stock [Line Items]
Weighted average interest rate		16.21%
Interstate Battery System International, Inc. \| Merrill Lynch US High Yield B
Class of Stock [Line Items]
Weighted average interest rate		7.44%
Interstate Battery System International, Inc. \| Warrant 1
Class of Stock [Line Items]
Warrant shares issued (in shares)				702,247								702,247
Warrant exercise price (in dollars per share)				$ 7.12								$ 7.12
Share price (in dollars per share)				$ 11.39								$ 11.39
Interstate Battery System International, Inc. \| Warrant 2
Class of Stock [Line Items]
Warrant shares issued (in shares)				1,605,131								1,605,131
Warrant exercise price (in dollars per share)				$ 9.00								$ 9.00
Share price (in dollars per share)				11.39								11.39
Interstate Battery Systems International, Inc.
Class of Stock [Line Items]
Repayments of convertible debt	$ 6,700,000
Amortization of debt discount	2,600,000
Amortization of deferred financing expenses	$ 20,000
Credit Agreement \| Interstate Battery System International, Inc.
Class of Stock [Line Items]
Warrant exercise price (in dollars per share)				$ 3.33								$ 3.33
Amortized period to interest expense			3 years
Credit Agreement \| Secured Debt \| Interstate Battery System International, Inc.
Class of Stock [Line Items]
General and administrative expense														$ 600,000
Securities Purchase Agreement \| Interstate Battery System International, Inc.
Class of Stock [Line Items]
Common stock issued (in shares)			702,247
Proceeds from issuance of common stock, net of transaction costs			$ 5,000,000.0
Share price (in dollars per share)			$ 7.12
11% Convertible Notes
Class of Stock [Line Items]
Convertible note payable				$ 5,000,000.0								$ 5,000,000.0
Convertible note interest rate				11.00%								11.00%
Conversion price (in dollars per share)				$ 7.12								$ 7.12
11% Convertible Notes \| Interstate Battery System International, Inc.
Class of Stock [Line Items]
Conversion price (in dollars per share)				$ 7.22								$ 7.22