Consolidated Statements of Changes in Equity, Accumulated Other Comprehensive Income (Loss) and Redeemable Non-Controlling Interest - USD ($) $ in Millions	Total	Common Stock	Treasury Stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	Non- Controlling Interest in Consolidated Subsidiaries	Redeemable Non-controlling Interest
Beginning balance (in shares) at Dec. 31, 2014		579,000,000	19,000,000
Beginning balance at Dec. 31, 2014	$ 12,392	$ 6	$ (743)	$ 9,933	$ 3,210	$ (46)	$ 32	$ 165
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Other comprehensive Income (loss)	(142)					(142)
Stock consideration issued for Interactive Data and Trayport acquisitions (in shares)		45,000,000
Stock consideration issued for Interactive Data and Trayport acquisitions	2,197		$ 0	2,197
Exercise of common stock options	$ 19			19
Repurchases of common stock (in shares)	(14,343,845)		(14,000,000)
Repurchases of common stock	$ (660)		$ (660)
Payments relating to treasury shares (in shares)	(979,295)		(1,000,000)
Payments relating to treasury shares	$ (45)		$ (45)
Stock-based compensation	122			122
Issuance of restricted stock (in shares)		4,000,000
Tax benefits from stock option plans	19			19
Adjustment to redemption value	(5)				(5)			4
Distributions of profits	(16)						(16)	(11)
Dividends paid to shareholders	(331)				(331)
Purchase of subsidiary shares	0			0			0	(128)
Net income attributable to non-controlling interest	(5)				(21)		16	5
Net income	1,295				1,295
Ending balance (in shares) at Dec. 31, 2015		628,000,000	34,000,000
Ending balance at Dec. 31, 2015	14,840	$ 6	$ (1,448)	12,290	4,148	(188)	32	35
Accumulated other comprehensive income (loss) was as follows:
Foreign currency translation adjustments	(45)
Fair value of available-for-sale securities	(26)
Comprehensive income from equity method investment	2
Employee benefit plans adjustments	(119)
Accumulated other comprehensive loss	(188)
Other comprehensive Income (loss)	(156)					(156)
Exercise of common stock options (in shares)		1,000,000
Exercise of common stock options	22			22
Treasury shares retired in connection with stock split (in shares)		35,000,000	35,000,000
Treasury shares retired in connection with stock split	$ 0		$ 1,512	(1,142)	(370)
Repurchases of common stock (in shares)	(902,920)		(1,000,000)
Repurchases of common stock	$ (50)		$ (50)
Payments relating to treasury shares (in shares)	(1,074,162)		(1,000,000)
Payments relating to treasury shares	$ (54)		$ (54)
Stock-based compensation	136			136
Issuance of restricted stock (in shares)		2,000,000
Adjustment to redemption value	(2)				(2)			1
Distributions of profits	(19)						(19)	(3)
Dividends paid to shareholders	(409)				(409)
Net income attributable to non-controlling interest	(3)				(27)		24	3
Net income	$ 1,449				1,449
Ending balance (in shares) at Dec. 31, 2016	596,000,000	596,000,000	1,000,000
Ending balance at Dec. 31, 2016	$ 15,754	$ 6	$ (40)	11,306	4,789	(344)	37	36
Accumulated other comprehensive income (loss) was as follows:
Foreign currency translation adjustments	(345)
Fair value of available-for-sale securities	108
Comprehensive income from equity method investment	2
Employee benefit plans adjustments	(109)
Accumulated other comprehensive loss	(344)
Other comprehensive Income (loss)	121					121
Exercise of common stock options	$ 17			17
Repurchases of common stock (in shares)	(14,966,616)		(15,000,000)
Repurchases of common stock	$ (949)		$ (949)
Payments relating to treasury shares (in shares)	(1,503,453)		(1,000,000)
Payments relating to treasury shares	$ (88)		$ (88)
Stock-based compensation	152			152
Issuance of restricted stock (in shares)		4,000,000
Stock-based compensation	0		$ 1	(1)
Acquisition of non-controlling interest	(92)			(82)	0		(10)	0
Distributions of profits	(26)						(26)	0
Dividends paid to shareholders	(476)				(476)
Acquisition of redeemable non-controlling interest	(2)			0	(2)		0	(37)
Net income attributable to non-controlling interest	(1)				(28)		27	1
Net income	$ 2,542				2,542
Ending balance (in shares) at Dec. 31, 2017	600,000,000	600,000,000	17,000,000
Ending balance at Dec. 31, 2017	$ 16,952	$ 6	$ (1,076)	$ 11,392	$ 6,825	$ (223)	$ 28	$ 0
Accumulated other comprehensive income (loss) was as follows:
Foreign currency translation adjustments	(136)
Fair value of available-for-sale securities	0
Comprehensive income from equity method investment	2
Employee benefit plans adjustments	(89)
Accumulated other comprehensive loss	$ (223)