SEGMENT INFORMATION - Schedule of Expenses by Segment (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2026	Sep. 30, 2025	Sep. 30, 2026	Sep. 30, 2025
Segment Reporting [Line Items]
Total research and development expense	$ 408,538	$ 358,814	$ 1,186,538	$ 947,557
Total selling, general and administrative expense	342,000	322,076	1,012,473	885,339
Single Reportable Segment
Segment Reporting [Line Items]
Total research and development expense	408,538	358,814	1,186,538	947,557
Total selling, general and administrative expense	342,000	322,076	1,012,473	885,339
Compensation and related \| Single Reportable Segment
Segment Reporting [Line Items]
Total selling, general and administrative expense	167,544	188,669	497,240	511,339
Consulting and professional services \| Single Reportable Segment
Segment Reporting [Line Items]
Total selling, general and administrative expense	118,917	88,738	344,815	236,062
Occupancy and all other costs \| Single Reportable Segment
Segment Reporting [Line Items]
Total selling, general and administrative expense	55,539	44,669	170,418	137,938
Clinical research and outside services \| Single Reportable Segment
Segment Reporting [Line Items]
Total research and development expense	239,525	170,756	683,008	438,791
Compensation and related \| Single Reportable Segment
Segment Reporting [Line Items]
Total research and development expense	121,722	146,089	371,410	388,726
Occupancy and all other costs \| Single Reportable Segment
Segment Reporting [Line Items]
Total research and development expense	$ 47,291	$ 41,969	$ 132,120	$ 120,040