Loans Payable and Long-Term Debt	6 Months Ended
Jun. 30, 2026
Debt Disclosure [Abstract]
Loans Payable and Long-Term Debt	Loans Payable and Long-Term Debt In April 2026, Merck entered into a delayed draw term loan credit agreement (Credit Agreement) pursuant to which the lenders committed (subject to satisfaction of certain conditions set forth in the Credit Agreement) to provide Merck with financing under a 364-day term loan facility in an aggregate amount not to exceed $6.0 billion. The Company drew down the full $6.0 billion of funds under the facility to fund a portion of the approximately $6.8 billion cash consideration for the acquisition of Terns. The Company has since repaid borrowings under the Credit Agreement. In May 2026, the Company issued $6.0 billion aggregate principal amount of senior unsecured notes consisting of $500 million of floating rate notes due 2028, $1.0 billion of 4.30% notes due 2028, $500 million of 4.65% notes due 2031, $1.0 billion of 4.95% notes due 2033, $1.5 billion of 5.20% notes due 2036, $500 million of 5.75% notes due 2046, and $1.0 billion of 5.85% notes due 2056. The Company used the net proceeds from the offering to repay borrowings under the Credit Agreement as noted above.

In April 2026, Merck entered into a delayed draw term loan credit agreement (Credit Agreement) pursuant to which the lenders committed (subject to satisfaction of certain conditions set forth in the Credit Agreement) to provide Merck with financing under a 364-day term loan facility in an aggregate amount not to exceed $6.0 billion. The Company drew down the full $6.0 billion of funds under the facility to fund a portion of the approximately $6.8 billion cash consideration for the acquisition of Terns. The Company has since repaid borrowings under the Credit Agreement.

In May 2026, the Company issued $6.0 billion aggregate principal amount of senior unsecured notes consisting of $500 million of floating rate notes due 2028, $1.0 billion of 4.30% notes due 2028, $500 million of 4.65% notes due 2031, $1.0 billion of 4.95% notes due 2033, $1.5 billion of 5.20% notes due 2036, $500 million of 5.75% notes due 2046, and $1.0 billion of 5.85% notes due 2056. The Company used the net proceeds from the offering to repay borrowings under the Credit Agreement as noted above.