Goodwill and Intangible Assets (Tables)

3 Months Ended

Mar. 31, 2017

Goodwill and Intangible Assets Disclosure [Abstract]

Schedule of changes to the carrying amount of goodwill by reporting unit

The following table presents changes to the carrying amount of goodwill by reportable segment during the three months ended March 31, 2017 (in thousands):

	Research		Consulting		Events		Total
Balance, December 31, 2016 (1)	$	595,450	$	96,480	$	46,523	$	738,453
Additions due to acquisitions (2)	114,222		—		—		114,222
Foreign currency translation adjustments	2,376		197		82		2,655
Balance, March 31, 2017	$	712,048	$	96,677	$	46,605	$	855,330

(1) The Company does not have any accumulated goodwill impairment losses.

(2) The addition to goodwill was due to the acquisition of L2 in March 2017.

Schedule of amortizable intangible assets

The following tables present reconciliations of the carrying amounts of the Company's finite-lived intangible assets as of the dates indicated (in thousands):

March 31, 2017	Trade Names			Customer Relationships			Content			Software			Non-Compete			Total
Gross cost	$	4,337		$	63,369		$	3,728		$	16,025		$	29,308		$	116,767
Additions due to acquisition (1)	500			9,000			—			1,000			—			10,500
Foreign currency translation impact	20			190			37			42			25			314
Gross cost	4,857			72,559			3,765			17,067			29,333			127,581
Accumulated amortization (2), (3)	(2,046		)	(19,469		)	(2,521		)	(10,266		)	(12,070		)	(46,372		)
Balance, March 31, 2017	$	2,811		$	53,090		$	1,244		$	6,801		$	17,263		$	81,209

December 31, 2016	Trade Names			Customer Relationships			Content			Software			Non-Compete			Total
Gross cost	$	4,337		$	63,369		$	3,728		$	16,025		$	29,308		$	116,767
Accumulated amortization (2), (3)	(1,737		)	(16,744		)	(2,033		)	(8,904		)	(10,548		)	(39,966		)
Balance, December 31, 2016	$	2,600		$	46,625		$	1,695		$	7,121		$	18,760		$	76,801

(1) The additions are due to the acquisition of L2 in March 2017.

(2) Intangible assets are amortized against earnings over the following periods: Trade names—2 to 4 years; Customer relationships—4 to 8 years; Content—1.5 to 2 years; Software—3 years; Non-compete—3 to 5 years.

(3) Aggregate amortization expense related to intangible assets was $6.3 million and $6.2 million for the three months ended March 31, 2017 and 2016, respectively

Schedule of estimated future amortization expense by year

The estimated future amortization expense by year from finite-lived intangibles will be as follows (in thousands):

2017 (remaining nine months)	$	18,508
2018	21,836
2019	16,624
2020	14,116
2021	6,533
Thereafter	3,592
	$	81,209