Goodwill and Intangible Assets (Tables)

6 Months Ended

Jun. 30, 2021

Goodwill and Intangible Assets Disclosure [Abstract]

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

The table below presents changes to the carrying amount of goodwill by segment during the six months ended June 30, 2021 (in thousands).

	Research		Conferences		Consulting		Total
Balance at December 31, 2020 (1)	$	2,664,732	$	184,091	$	96,724	$	2,945,547
Additions due to an acquisition (2)	11,172		—		—		11,172
Foreign currency translation impact	(1,398)		(20)		165		(1,253)
Balance at June 30, 2021 (1)	$	2,674,506	$	184,071	$	96,889	$	2,955,466

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

(2)The additions were due to the acquisition of Pulse on June 17, 2021. See Note 2 — Acquisition for additional information.

Schedule of amortizable intangible assets

The tables below present reconciliations of the carrying amounts of the Company’s finite-lived intangible assets as of the dates indicated (in thousands).

June 30, 2021	Customer Relationships		Software		Content		Other		Total
Gross cost at December 31, 2020	$	1,154,210	$	110,597	$	3,965	$	10,614	$	1,279,386
Additions due to an acquisition (1)	7,980		11,200		—		280		19,460
Intangible assets fully amortized	(17,788)		(60,631)		(3,965)		—		(82,384)
Foreign currency translation impact	7,895		226		—		—		8,121
Gross cost	1,152,297		61,392		—		10,894		1,224,583
Accumulated amortization (2)	(414,460)		(30,394)		—		(4,250)		(449,104)
Balance at June 30, 2021	$	737,837	$	30,998	$	—	$	6,644	$	775,479

December 31, 2020	Customer Relationships		Software		Content		Other		Total
Gross cost	$	1,154,210	$	110,597	$	3,965	$	10,614	$	1,279,386
Accumulated amortization (2)	(381,776)		(83,320)		(3,595)		(3,697)		(472,388)
Balance at December 31, 2020	$	772,434	$	27,277	$	370	$	6,917	$	806,998

(1) The additions were due to the acquisition of Pulse on June 17, 2021. See Note 2 — Acquisition for additional information.

(2) Finite-lived intangible assets are amortized using the straight-line method over the following periods: Customer relationships—6 to 13 years; Software—3 to 7 years; Content—2 to 3 years; and Other—2 to 11 years.

Schedule of estimated future amortization expense by year

The estimated future amortization expense by year for finite-lived intangible assets is presented in the table below (in thousands).

2021 (remaining six months)	$	52,600
2022	101,768
2023	101,752
2024	94,540
2025	84,001
Thereafter	340,818
	$	775,479