Stock Based Compensation, Share Option Valuation (Details) - Stock Options [Member] - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Stock Option Activity [Roll Forward]
Outstanding at beginning of period (in shares)	11,050,931
Granted (in shares)	916,575
Exercised (in shares)	(991,432)
Cancelled (in shares)	(83,244)
Outstanding at end of period (in shares)	10,892,830		11,050,931
Options vested and exercisable at end of period (in shares)	7,856,137
Options unvested at ending of period (in shares)	3,036,693
Weighted Average Exercise Price [Abstract]
Outstanding at beginning of period (in dollars per share)	$ 9.10
Granted (in dollars per share)	60.95
Exercised (in dollars per share)	8.31
Cancelled (in dollars per share)	31.82
Outstanding at end of period (in dollars per share)	13.42		$ 9.10
Options vested and exercisable at end of period (in dollars per share)	5.70
Options unvested at ending (in dollars per share)	$ 33.17
Weighted-Average Remaining Contractual Term [Abstract]
Outstanding	6 years 6 months 25 days		6 years 6 months 18 days
Granted	10 years 7 months 20 days
Options vested and exercisable	5 years 6 months 18 days
Options unvested	9 years 2 months 12 days
Aggregate Intrinsic Value [Abstract]
Outstanding at beginning of period	$ 504,079
Exercised	51,892
Outstanding at end of period	349,406		$ 504,079
Options vested and exercisable	$ 300,452
Weighted average grant date fair value of shares granted (in dollars per share)	$ 36.99	$ 15.03
Total fair value of options vested	$ 8,300	$ 17,300
Employees and Directors [Member]
Weighted-Average Assumptions [Abstract]
Risk-free interest rate	0.62%	1.48%
Expected term	5 years 10 months 13 days	5 years 10 months 13 days
Expected volatility	69.41%	77.75%
Expected dividend yield	0.00%	0.00%
Exercise price (in dollars per share)	$ 36.99	$ 22.47
Fair value of common stock (in dollars per share)	$ 36.99	$ 22.47