Goodwill and Other Intangible Assets (Tables)

12 Months Ended

Dec. 31, 2016

Goodwill And Intangible Assets Disclosure [Abstract]

Summary of Changes in Carrying Amount of Goodwill

The table below summarizes the changes in the carrying amount of goodwill by reportable segment for the years ended December 31, 2016 and 2015, respectively.

(IN MILLIONS)	Buy			Watch			Total
Balance, December 31, 2014	$	3,014		$	4,657		$	7,671
Acquisitions, divestitures and other adjustments		4			361			365
Effect of foreign currency translation		(229	)		(24	)		(253	)
Balance, December 31, 2015	$	2,789		$	4,994		$	7,783
Acquisitions, divestitures and other adjustments		(31	)		170			139
Effect of foreign currency translation		(62	)		(15	)		(77	)
Balance, December 31, 2016	$	2,696		$	5,149		$	7,845
Cumulative impairments	$	—		$	376		$	376

Other Intangible Assets

The table below summarizes the carrying value of such intangible assets and their estimated useful lives:

			Gross Amounts				Accumulated Amortization
	Estimated	Weighted	December 31,		December 31,		December 31,			December 31,
(IN MILLIONS)	Useful Lives	Average	2016		2015		2016			2015
Indefinite-lived intangibles:
Trade names and trademarks			$	1,921	$	1,921	$	—		$	—
Amortized intangibles:
Trade names and trademarks	5-20 years	13 years		140		167		(88	)		(84	)
Customer-related intangibles	6-25 years	21 years		3,035		3,013		(1,312	)		(1,193	)
Covenants-not-to-compete	1-7 years	3 years		39		37		(36	)		(35	)
Computer software	3-10 years	5 years		2,223		1,919		(1,258	)		(1,055	)
Patents and other	3-10 years	6 years		173		168		(101	)		(86	)
Total			$	5,610	$	5,304	$	(2,795	)	$	(2,453	)

Summary of Estimated Future Amortization Expense

All other intangible assets are subject to amortization. Future amortization expense is estimated to be as follows:

(IN MILLIONS)
For the year ending December 31:
2017	$	399
2018		419
2019		353
2020		316
2021		296
Thereafter		1,032
Total	$	2,815