Convertible Notes Payable (Details)			1 Months Ended	12 Months Ended
	Jun. 12, 2020 USD ($)	Feb. 20, 2020 USD ($) $ / shares shares	Dec. 31, 2020 USD ($) $ / shares shares	Dec. 31, 2020 USD ($) d $ / shares	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Jan. 04, 2018 USD ($)
Debt [Abstract]
Convertible notes refinancing costs to the lender				$ 237,000	$ 0	$ 0
Conversion of convertible notes into common stock				7,629,000	0	0
Carrying value of convertible notes [Abstract]
Carrying value			$ 35,066,000	35,066,000	45,049,000
Accretion of debt discount				$ 2,758,000	3,602,000	3,059,000
2021 Convertible Notes [Member]
Debt [Abstract]
Debt instrument maturity date				Aug. 01, 2021
Convertible senior notes, interest rate, stated percentage	6.25%		5.75%	5.75%
Debt conversion ratio				31.1876
Conversion per principal amount of debt			$ 1,000.00	$ 1,000.00
Convertible Note exchange	1.00
Conversion price (in dollars per share) | $ / shares			$ 32.08	$ 32.08
Percentage of common stock conversion price				200.00%
Number of trading days, not consecutive | d				20
Number of consecutive trading days | d				30
Number of trading days immediately preceding notice of redemption				5 days
Redemption price percentage				100.00%
Effective interest rate			15.30%	15.30%
Debt instrument, aggregate principal amount exchanged	$ 7,500,000	$ 39,350,000
Debt instrument, percentage of aggregate outstanding principal		76.00%
Accrued and unpaid interest	11,000	$ 100,000
Number of common stock shares repurchased (in shares) | shares		3,000
Aggregate amount of common stock shares repurchased		$ 72,000
Cost associated with exchange transactions	300,000	$ 1,600,000
Carrying value of convertible notes [Abstract]
Principal amount	7,500,000		$ 5,150,000	$ 5,150,000	52,000,000		$ 52,000,000.0
Discount			(275,000)	(275,000)	(6,951,000)
Carrying value			$ 4,875,000	4,875,000	45,049,000
Accretion of debt discount				$ 1,300,000	$ 3,600,000	$ 3,100,000
2022 Convertible Notes [Member]
Debt [Abstract]
Debt instrument maturity date				Aug. 31, 2022
Convertible senior notes, interest rate, stated percentage		6.25%	6.25%	6.25%
Debt conversion ratio		31.1876
Conversion per principal amount of debt		$ 1,000.00
Convertible Note exchange		1.00
Conversion price (in dollars per share) | $ / shares		$ 32.06
Percentage of common stock conversion price		130.00%
Number of trading days, not consecutive | d				20
Number of consecutive trading days | d				30
Number of trading days immediately preceding notice of redemption				5 days
Effective interest rate			15.30%	15.30%
Convertible notes refinancing costs to the lender	$ 100,000	$ 100,000
Conversion of convertible notes into common stock, principal amount			$ 8,500,000
Conversion of convertible notes into common stock			$ 7,600,000
Convertible Notes converted into shares of common stock (in shares) | shares			298,562
Carrying value of convertible notes [Abstract]
Principal amount		$ 39,350,000	$ 38,350,000	$ 38,350,000
Discount			(3,284,000)	(3,284,000)
Carrying value			$ 35,066,000	35,066,000
Accretion of debt discount				$ 1,500,000