Goodwill and other intangible assets - Change in Goodwill (Detail) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2019	Dec. 30, 2018	Dec. 31, 2017
Goodwill [Roll Forward]
Beginning Balance	$ 310,737	$ 236,555
Goodwill acquired in business combinations	665,616	73,726
Measurement period adjustments	(852)	456
Impairment loss	(62,280)
Goodwill related to divestitures	(42)
Foreign currency exchange rate changes	1,152
Ending Balance	914,331	310,737
Goodwill accumulated impairment losses	87,921	25,641	$ 25,641
Publishing
Goodwill [Roll Forward]
Beginning Balance	280,295	208,828
Goodwill acquired in business combinations	498,061	71,011
Measurement period adjustments	(852)	456
Impairment loss	(62,280)
Goodwill related to divestitures	(42)
Foreign currency exchange rate changes	1,152
Ending Balance	716,334	280,295
Marketing Solutions
Goodwill [Roll Forward]
Beginning Balance	30,442	27,727
Goodwill acquired in business combinations	167,555	2,715
Measurement period adjustments	0	0
Impairment loss	0
Goodwill related to divestitures	0
Foreign currency exchange rate changes	0
Ending Balance	$ 197,997	$ 30,442

Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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