Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Statement of Comprehensive Income [Abstract]
Net income	$ 501	$ 457	$ 1,035	$ 887
Other comprehensive income:
Foreign currency translation adjustment	(75)	42	(52)	72
Income tax effect	15	0	(3)	0
Foreign currency translation adjustment, net of income tax effect	(60)	42	(55)	72
Pension and other postretirement benefit plans	(15)	0	(11)	4
Income tax effect	4	2	3	1
Pension and other postretirement benefit plans, net of income tax effect	(11)	2	(8)	5
Unrealized gain (loss) on investment and forward exchange contracts	(5)	(10)	(4)	(3)
Income tax effect	1	2	1	0
Unrealized gain on forward exchange contracts, net of income tax effect	(4)	(8)	(3)	(3)
Comprehensive income	426	493	969	961
Less: comprehensive income attributable to nonredeemable noncontrolling interests	(5)	(5)	(8)	(6)
Less: comprehensive income attributable to redeemable noncontrolling interests	(36)	(31)	(76)	(61)
Comprehensive income attributable to S&P Global Inc.	$ 385	$ 457	$ 885	$ 894