Shareholders' equity - Schedule of Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	$ 2,704,872
Amounts classified from AOCL	12,142	$ 4,154	$ (12,106)
Ending Balance	3,004,714	2,704,872
Equity method investments	16,280	16,195
CareerBuilder Investment
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Equity method investments	0
Total
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	(119,610)	(125,533)	(97,216)
Other comprehensive income (loss), before reclassifications	824	1,769	(16,211)
Amounts classified from AOCL	12,142	4,154	(12,106)
Ending Balance	(106,644)	(119,610)	(125,533)
Retirement Plans
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	(120,142)	(126,065)	(113,090)
Other comprehensive income (loss), before reclassifications	824	1,769	(16,288)
Amounts classified from AOCL	12,142	4,154	3,313
Ending Balance	(107,176)	(120,142)	(126,065)
Foreign Currency Translation
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	532	532	455
Other comprehensive income (loss), before reclassifications	0	0	77
Amounts classified from AOCL	0	0	0
Ending Balance	$ 532	532	532
Available-For-Sale Investment
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance		$ 0	15,419
Other comprehensive income (loss), before reclassifications
Amounts classified from AOCL			(15,419)
Ending Balance			$ 0