Consolidated Statement of Comprehensive Income - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Statement of Comprehensive Income [Abstract]
Net Income Attributable to Merck & Co., Inc.	$ 3,920	$ 4,442	$ 11,920
Other Comprehensive Income (Loss) Net of Taxes:
Net unrealized (loss) gain on derivatives, net of reclassifications	(66)	(126)	398
Net unrealized (loss) gain on investments, net of reclassifications	(44)	(70)	57
Benefit plan net (loss) gain and prior service (cost) credit, net of amortization	(799)	579	(2,077)
Cumulative translation adjustment	(169)	(208)	(504)
Other comprehensive income (loss), net of taxes	(1,078)	175	(2,126)
Comprehensive Income Attributable to Merck & Co., Inc.	$ 2,842	$ 4,617	$ 9,794