Income taxes - Provision for Taxes on Income (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Pretax income
Domestic	$ 217,098	$ 225,442	$ 168,180
Foreign	163,668	153,089	146,374
Income before income taxes	380,766	378,531	314,554
Current
Federal	14,933	37,345	120,398
State	2,565	6,164	5,623
Foreign	45,911	38,648	40,328
Total current	63,409	82,157	166,349
Deferred
Federal	25,064	(5,571)	(16,797)
State	8,599	(738)	3,499
Foreign	(3,803)	(840)	(6,462)
Total deferred	29,860	(7,149)	(19,760)
Total taxes	$ 93,269	$ 75,008	$ 146,589