Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Statement of Comprehensive Income [Abstract]
Net income	$ 453	$ 534
Other comprehensive income:
Foreign currency translation adjustment	17	23
Income tax effect	2	(18)
Foreign currency translation adjustment, net of income tax effect	19	5
Pension and other postretirement benefit plans	114	4
Income tax effect	(28)	(1)
Pension and other postretirement benefit plans, net of income tax effect	86	3
Unrealized gain on investment and forward exchange contracts	5
Income tax effect	(1)
Unrealized gain on investment and forward exchange contracts, net of income tax effect	4
Unrealized gain on investment and forward exchange contracts		1
Income tax effect		0
Unrealized gain on investment and forward exchange contracts, net of income tax effect		1
Comprehensive income	562	543
Less: comprehensive income attributable to nonredeemable noncontrolling interests	(3)	(3)
Less: comprehensive income attributable to redeemable noncontrolling interests	(40)	(40)
Comprehensive income attributable to S&P Global Inc.	$ 519	$ 500