Fair value measurements Insurance contracts (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021	Dec. 31, 2021
Fair Value Disclosures [Abstract]
Investments used to satisfy nonqualified benefit plans obligations	$ 95,200,000	$ 106,400,000	$ 95,200,000	$ 106,400,000	$ 109,600,000
Net unrealized gain (loss) on investments used to satisfy obligations under nonqualified benefit plans	$ 2,600,000	$ 373,000	$ 16,800,000	$ 4,200,000