v3.25.1
Financial Instruments and Fair Value Measures - Debt and Credit Facilities (Details) - USD ($)
$ in Millions
3 Months Ended
Mar. 31, 2025
Sep. 30, 2024
Mar. 31, 2024
Jun. 30, 2025
May 09, 2025
Dec. 31, 2024
Feb. 12, 2024
Dec. 21, 2023
Dec. 06, 2023
Short-Term Borrowings [Line Items]                  
Short-term borrowings $ 1,593         $ 0      
Proceeds from issuance of other short-term borrowings 0   $ 5,008            
Repayments of other short-term borrowings 0   $ 5,005            
Commercial paper                  
Short-Term Borrowings [Line Items]                  
Short-term borrowings $ 1,600                
Short-Term Debt, Weighted Average Interest Rate, over Time 4.59%   5.54%            
December 2023 Bridge Credit Facility                  
Short-Term Borrowings [Line Items]                  
Line of Credit Facility, Maximum Borrowing Capacity                 $ 9,000
364-day Term Loan Credit Agreement                  
Short-Term Borrowings [Line Items]                  
Line of Credit Facility, Maximum Borrowing Capacity               $ 5,000  
364-day Term Loan Credit Agreement | Subsequent event                  
Short-Term Borrowings [Line Items]                  
Line of Credit Facility, Maximum Borrowing Capacity       $ 4,000          
364 Day Term loan agreement | Subsequent event                  
Short-Term Borrowings [Line Items]                  
Short-term borrowings         $ 0        
Term loan facilities                  
Debt and Credit Facilities [Line Items]                  
Long-Term Debt, Weighted Average Interest Rate, over Time   6.29%              
Senior Notes Issued in 2024                  
Debt and Credit Facilities [Line Items]                  
Debt Issuance Costs, Gross     $ 99            
Debt Instrument, Unamortized Discount     37            
Senior Notes Issued in 2024 | Senior notes                  
Debt and Credit Facilities [Line Items]                  
Aggregate principal amount of debt     15,000            
December 2023 Term Loan Credit Agreement                  
Debt and Credit Facilities [Line Items]                  
Debt Instrument, Basis Spread on Variable Rate   0.975%              
Short-Term Borrowings [Line Items]                  
Proceeds from Other Short-Term Debt     5,000            
Repayments of other short-term borrowings     $ 5,000            
3.80% Senior Notes | Senior notes                  
Debt and Credit Facilities [Line Items]                  
Stated interest rate (as a percent) 3.80%                
3.80% Senior Notes | Term loan facilities                  
Debt and Credit Facilities [Line Items]                  
Repayments of long-term debt $ (3,000)                
4.65% Senior Notes due 2028 | Senior notes                  
Debt and Credit Facilities [Line Items]                  
Aggregate principal amount of debt 1,250                
4.875% Senior Notes due 2030 | Senior notes                  
Debt and Credit Facilities [Line Items]                  
Aggregate principal amount of debt 1,000                
5.20% Senior Notes due 2035 | Senior notes                  
Debt and Credit Facilities [Line Items]                  
Aggregate principal amount of debt 1,000                
5.60% Senior Notes due 2055 | Senior notes                  
Debt and Credit Facilities [Line Items]                  
Aggregate principal amount of debt 750                
Senior Notes Issued in 2025 | Senior notes                  
Debt and Credit Facilities [Line Items]                  
Aggregate principal amount of debt 4,000                
ImmunoGen Senior Secured Term Loan                  
Debt and Credit Facilities [Line Items]                  
Other Long-Term Debt             $ (99)    
Revolving Credit Facility                  
Short-Term Borrowings [Line Items]                  
Long-Term Line of Credit $ 0         $ 0      
Revolving Credit Facility Maturing 2028                  
Short-Term Borrowings [Line Items]                  
Line of Credit Facility, Expiration Period 5 years                
Line of Credit Facility, Maximum Borrowing Capacity $ 5,000                
Revolving Credit Facility Maturing 2030                  
Short-Term Borrowings [Line Items]                  
Line of Credit Facility, Expiration Period 5 years                
Line of Credit Facility, Maximum Borrowing Capacity $ 3,000