Goodwill and intangible assets - Schedule of Intangible Assets (Detail) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Finite-Lived Intangible Assets
Gross carrying amount	$ 886,801	$ 887,645
Accumulated amortization	260,226	234,403
Finite-lived intangible assets, net	626,575	653,242
Intangible Assets
Total intangible assets	797,862	824,650
Goodwill	534,211	534,088
Mastheads
Intangible Assets
Non-amortized intangible assets	171,287	171,408
Advertiser relationships
Finite-Lived Intangible Assets
Gross carrying amount	459,570	460,331
Accumulated amortization	123,338	112,468
Finite-lived intangible assets, net	336,232	347,863
Other customer relationships
Finite-Lived Intangible Assets
Gross carrying amount	102,946	102,925
Accumulated amortization	26,642	23,682
Finite-lived intangible assets, net	76,304	79,243
Subscriber relationships
Finite-Lived Intangible Assets
Gross carrying amount	255,598	255,702
Accumulated amortization	78,558	71,271
Finite-lived intangible assets, net	177,040	184,431
Other intangible assets
Finite-Lived Intangible Assets
Gross carrying amount	68,687	68,687
Accumulated amortization	31,688	26,982
Finite-lived intangible assets, net	$ 36,999	$ 41,705