FAIR VALUE MEASUREMENTS - Fair Value, Assets and Liabilities Measured on Recurring Basis (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Short-term investments:
Short-term investments	$ 308,569	$ 424,450
Money market funds
Short-term investments:
Short-term investments	102,985	137,903
U.S. corporate paper and bonds
Short-term investments:
Short-term investments	161,216	198,966
U.S. treasury securities
Short-term investments:
Short-term investments	44,368	85,605
International corporate bond holdings
Short-term investments:
Short-term investments		1,976
Fair Value, Recurring
Short-term investments:
Total cash equivalents and short-term investments	308,569	424,450
Fair Value, Recurring | Money market funds
Cash equivalents:
Cash equivalents	102,985	137,903
Fair Value, Recurring | U.S. corporate paper and bonds
Cash equivalents:
Cash equivalents	4,173	17,576
Short-term investments:
Short-term investments	157,043	181,390
Fair Value, Recurring | U.S. treasury securities
Short-term investments:
Short-term investments	44,368	85,605
Fair Value, Recurring | International corporate bond holdings
Short-term investments:
Short-term investments		1,976
Fair Value, Recurring | Quoted Prices in Active Markets (Level 1)
Short-term investments:
Total cash equivalents and short-term investments	102,985	137,903
Fair Value, Recurring | Quoted Prices in Active Markets (Level 1) | Money market funds
Cash equivalents:
Cash equivalents	102,985	137,903
Fair Value, Recurring | Quoted Prices in Active Markets (Level 1) | U.S. corporate paper and bonds
Cash equivalents:
Cash equivalents	0	0
Short-term investments:
Short-term investments	0	0
Fair Value, Recurring | Quoted Prices in Active Markets (Level 1) | U.S. treasury securities
Short-term investments:
Short-term investments	0	0
Fair Value, Recurring | Quoted Prices in Active Markets (Level 1) | International corporate bond holdings
Short-term investments:
Short-term investments		0
Fair Value, Recurring | Significant Other Observable Inputs (Level 2)
Short-term investments:
Total cash equivalents and short-term investments	205,584	286,547
Fair Value, Recurring | Significant Other Observable Inputs (Level 2) | Money market funds
Cash equivalents:
Cash equivalents	0	0
Fair Value, Recurring | Significant Other Observable Inputs (Level 2) | U.S. corporate paper and bonds
Cash equivalents:
Cash equivalents	4,173	17,576
Short-term investments:
Short-term investments	157,043	181,390
Fair Value, Recurring | Significant Other Observable Inputs (Level 2) | U.S. treasury securities
Short-term investments:
Short-term investments	44,368	85,605
Fair Value, Recurring | Significant Other Observable Inputs (Level 2) | International corporate bond holdings
Short-term investments:
Short-term investments		1,976
Fair Value, Recurring | Significant Unobservable Inputs (Level 3)
Short-term investments:
Total cash equivalents and short-term investments	0	0
Fair Value, Recurring | Significant Unobservable Inputs (Level 3) | Money market funds
Cash equivalents:
Cash equivalents	0	0
Fair Value, Recurring | Significant Unobservable Inputs (Level 3) | U.S. corporate paper and bonds
Cash equivalents:
Cash equivalents	0	0
Short-term investments:
Short-term investments	0	0
Fair Value, Recurring | Significant Unobservable Inputs (Level 3) | U.S. treasury securities
Short-term investments:
Short-term investments	$ 0	0
Fair Value, Recurring | Significant Unobservable Inputs (Level 3) | International corporate bond holdings
Short-term investments:
Short-term investments		$ 0