Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement of Comprehensive Income [Abstract]
Net income	$ 2,121	$ 1,638	$ 2,228
Other comprehensive income:
Foreign currency translation adjustment	(96)	93	(132)
Income tax effect	(4)	0	(7)
Foreign currency translation adjustment, net of income tax effect	(100)	93	(139)
Pension and other postretirement benefit plans	(14)	52	(27)
Income tax effect	9	(11)	(10)
Pension and other postretirement benefit plans, net of income tax effect	(5)	41	(37)
Unrealized gain (loss) on investment and forward exchange contracts	2	(10)	4
Income tax effect	0	0	(1)
Unrealized loss on investment and forward exchange contracts, net of income tax effect	2	(10)	3
Comprehensive income	2,018	1,762	2,055
Less: comprehensive income attributable to nonredeemable noncontrolling interests	(12)	(13)	(13)
Less: comprehensive income attributable to redeemable noncontrolling interests	(151)	(129)	(109)
Comprehensive income attributable to S&P Global Inc.	$ 1,855	$ 1,620	$ 1,933