Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2022

Accounting Policies [Abstract]

Accounts Receivable, Allowance for Credit Losses

The following table shows the activity in the allowance for credit losses for the years ended December 31, 2022, 2021, and 2020:

	2022		2021		2020
Beginning balance	$	1,693	$	1,509	$	2,312
Charged to operating expenses	—		140		—
Write offs of accounts receivable, net of recoveries	(1,509)		44		(803)
Ending balance	184		1,693		1,509

Estimated Useful Lives of Property, Plant and Equipment

The estimated useful lives of these assets from continuing operations are as follows:

	Years
Land improvements	9–15
Buildings and building improvements	9–15
Furniture and fixtures	4–7
Equipment	2–7
Breeding stock	2
Computer hardware and software	1–7

Leasehold improvements are amortized over the shorter of the useful life of the asset or the applicable lease term, generally one to eleven years.

Summary of Assumptions Used in Option Pricing Model

The assumptions used in the Black-Scholes option pricing model for the years ended December 31, 2022, 2021, and 2020 are set forth in the table below:

	2022	2021	2020
Valuation assumptions
Expected dividend yield	0%	0%	0%
Expected volatility	87%–89%	87%–90%	59%–90%
Expected term (years)	6.25	6.00	6.00-10.00
Risk-free interest rate	1.64%–4.12%	0.61%–1.33%	0.36%–1.80%

Potentially Dilutive Securities Excluded from Calculation of Net Loss per Share

The following potentially dilutive securities as of December 31, 2022, 2021, and 2020, have been excluded from the computations of diluted weighted average shares outstanding for the years then ended as they would have been anti-dilutive: 

	December 31,
	2022	2021	2020
Options	15,201,276	12,260,187	11,255,896
Restricted stock units	697,815	468,481	1,727,712
Warrants	—	121,888	133,264
Total	15,899,091	12,850,556	13,116,872