Summary of Significant Accounting Policies (Policies)	6 Months Ended
Jun. 30, 2026
Accounting Policies [Abstract]
Recently Issued Accounting Pronouncements	Recently Issued Accounting Pronouncements In November 2024, the FASB issued an accounting standards update to improve disclosures regarding the types of expenses included in commonly presented expense captions, including disaggregating the amounts of employee compensation, depreciation and amortization included within each income statement expense caption. This standard will be effective for fiscal years beginning after December 15, 2026, and interim periods within fiscal years beginning after December 15, 2027. Cullinan will adopt this standard on January 1, 2027 for 2027 annual reporting and interim periods beginning in 2028 and is evaluating the impact of adopting this standard on its consolidated financial statements and disclosures.

Summary of Significant Accounting Policies (Policies)

6 Months Ended

Jun. 30, 2026

Recently Issued Accounting Pronouncements

In November 2024, the FASB issued an accounting standards update to improve disclosures regarding the types of expenses included in commonly presented expense captions, including disaggregating the amounts of employee compensation, depreciation and amortization included within each income statement expense caption. This standard will be effective for fiscal years beginning after December 15, 2026, and interim periods within fiscal years beginning after December 15, 2027. Cullinan will adopt this standard on January 1, 2027 for 2027 annual reporting and interim periods beginning in 2028 and is evaluating the impact of adopting this standard on its consolidated financial statements and disclosures.