OTHER BALANCE SHEET DETAILS - Schedule of Cash and Cash Equivalents (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Balance Sheet Related Disclosures [Abstract]
Cash and cash equivalents	$ 496,580	$ 547,178	$ 420,146
Total restricted cash included in prepaid expenses, other current assets and long-term other assets	2,466	2,450	2,485
Total cash, cash equivalents, and restricted cash shown in the consolidated statements of cash flows	$ 499,046	$ 549,628	$ 422,631	$ 646,832