CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE INCOME (LOSS) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Operating expenses:
Research and development	$ 30,646	$ 52,096
General and administrative	12,343	10,660
Total operating expenses	42,989	62,756
Loss from operations	(42,989)	(62,756)
Other income (expense):
Interest income	5,693	4,508
Other income (expense), net	(44)	107
Net loss	(37,340)	(58,141)
Net loss attributable to noncontrolling interests	(192)	(179)
Net loss attributable to common stockholders of Cullinan	(37,148)	(57,962)
Comprehensive income (loss):
Net loss	(37,340)	(58,141)
Unrealized gain (loss) on investments	(202)	1,359
Comprehensive loss	(37,542)	(56,782)
Comprehensive loss attributable to noncontrolling interests	(192)	(179)
Comprehensive loss attributable to Cullinan	$ (37,350)	$ (56,603)
Net loss per share attributable to common stockholders of Cullinan:
Net loss per share, basic	$ (0.86)	$ (1.42)
Net income loss per share, diluted	$ (0.86)	$ (1.42)
Weighted-average shares used in computing net income (loss) per share attributable to common stockholders of Cullinan
Weighted-average common stock outstanding - basic	43,011	40,682
Weighted-average common stock outstanding - diluted	43,011	40,682