Equity Plans - Employee Stock Purchase Plan 2016 ESPP (Details) - shares	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Jul. 31, 2016
ESPP shares
Equity Plans
Expected term (in year)	6 months	6 months	6 months
Expected volatility, Minimum	50.90%	89.10%	58.90%
Expected volatility, Maximum	69.70%	120.40%	65.30%
Risk-free interest rate, Minimum		0.12%	1.89%
Risk-free interest rate, Maximum		0.43%	2.32%
Risk-free interest rate	0.06%
2016 Employee Stock Purchase Plan
Equity Plans
Maximum payroll deduction for share purchases (as a percent)	15.00%
Purchase price of stock (as a percent)	85.00%
Shares issued in period	43,648
Number of shares available for issuance	1,013,999
Number of shares authorized				150,000
Maximum annual additional authorized shares as a percentage of outstanding shares	1.00%
Maximum annual additional authorized shares (in shares)	300,000