MARKETABLE SECURITIES (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 373,400	$ 189,428
Gross Unrealized Gains	21	890
Gross Unrealized Losses	(1,186)	0
Estimated Fair Market Value	$ 372,235	$ 190,318
Weighted Average Interest Rate on Investments	0.45%	0.89%
Interest receivable	$ 1,500	$ 800
Marketable securities, unrealized loss	0	0
Investments due in 3 months or less:
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	97,250	63,506
Gross Unrealized Gains	0	44
Gross Unrealized Losses	(3)	0
Estimated Fair Market Value	97,247	63,550
Investments due in 4-12 months:
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	25,054	125,922
Gross Unrealized Gains	0	846
Gross Unrealized Losses	(42)	0
Estimated Fair Market Value	25,012	126,768
Investments due in 12 months or greater:
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	251,096
Gross Unrealized Gains	21
Gross Unrealized Losses	(1,141)
Estimated Fair Market Value	249,976
Commercial paper | Investments due in 3 months or less:
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	89,965	43,660
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Estimated Fair Market Value	89,965	43,660
Corporate securities | Investments due in 3 months or less:
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	7,285	19,846
Gross Unrealized Gains	0	44
Gross Unrealized Losses	(3)	0
Estimated Fair Market Value	7,282	19,890
Corporate securities | Investments due in 4-12 months:
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	25,054	125,922
Gross Unrealized Gains	0	846
Gross Unrealized Losses	(42)	0
Estimated Fair Market Value	25,012	$ 126,768
Corporate securities | Investments due in 12 months or greater:
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	251,096
Gross Unrealized Gains	21
Gross Unrealized Losses	(1,141)
Estimated Fair Market Value	$ 249,976