Segments - Business Segment Information (Detail) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016
Segment Reporting Information [Line Items]
Revenues		$ 1,526	$ 1,487
Depreciation and amortization		155	147
Restructuring charges		32	10
Stock-based compensation expense		15	13
Other items	[1]	13	8
Operating income/(loss)		207	224
Business segment income/(loss)	[2]	422	402
Total assets		16,332		$ 15,730
Operating Segments | Buy
Segment Reporting Information [Line Items]
Revenues		757	793
Depreciation and amortization		50	51
Restructuring charges		20	6
Stock-based compensation expense		4	4
Other items	[1]		1
Operating income/(loss)		34	52
Business segment income/(loss)	[2]	108	114
Total assets		6,639		6,697
Operating Segments | Watch
Segment Reporting Information [Line Items]
Revenues		769	694
Depreciation and amortization		104	95
Restructuring charges		7	2
Stock-based compensation expense		4	3
Operating income/(loss)		208	197
Business segment income/(loss)	[2]	323	297
Total assets		9,734		8,905
Corporate
Segment Reporting Information [Line Items]
Depreciation and amortization		1	1
Restructuring charges		5	2
Stock-based compensation expense		7	6
Other items	[1]	13	7
Operating income/(loss)		(35)	(25)
Business segment income/(loss)	[2]	(9)	$ (9)
Total assets		$ (41)		$ 128

[1] Other items primarily consist of transaction related costs and business optimization costs for the three months ended March 31, 2017 and 2016.

[2] The Company’s chief operating decision maker uses business segment income/(loss) to measure performance from period to period both at the consolidated level as well as within its operating segments.