Consolidated Statement of Income - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Statement [Abstract]
Sales	$ 39,498	$ 42,237	$ 44,033
Costs, Expenses and Other
Materials and production	14,934	16,768	16,954
Marketing and administrative	10,313	11,606	11,911
Research and development	6,704	7,180	7,503
Restructuring costs	619	1,013	1,709
Other (income) expense, net	1,527	(11,613)	411
Total Costs, Expenses and Other	34,097	24,954	38,488
Income Before Taxes	5,401	17,283	5,545
Taxes on Income	942	5,349	1,028
Net Income	4,459	11,934	4,517
Less: Net Income Attributable to Noncontrolling Interests	17	14	113
Net Income Attributable to Merck & Co., Inc.	$ 4,442	$ 11,920	$ 4,404
Basic Earnings per Common Share Attributable to Merck & Co., Inc. Common Shareholders (in dollars per share)	$ 1.58	$ 4.12	$ 1.49
Earnings per Common Share Assuming Dilution Attributable to Merck & Co., Inc. Common Shareholders (in dollars per share)	$ 1.56	$ 4.07	$ 1.47