Reorganization and Reverse Stock Split - Summary of LLC Units Previously Reported as Redeemable Preferred Units or Temporary Equity Converted Reclassified to Equity (Details) - USD ($) $ in Thousands	Jun. 30, 2022	Mar. 31, 2022	Dec. 31, 2021	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020
Stockholders' Equity (Members' Deficit)
Common Stock	$ 5		$ 4
Additional paid-in capital	604,275		584,714
Accumulated other comprehensive loss	(3,633)		(838)
Retained earnings (accumulated deficit)	3,891		(158,909)
Total Cullinan Stockholders' Equity (Members' Deficit)	604,538		424,971
Non-controlling interests in subsidiaries	80		403
Total Stockholders' Equity (Members' Deficit)	$ 604,618	$ 419,470	$ 425,374	$ 458,540	$ 469,699	$ 200,314