Guarantees (Details 3)	Sep. 30, 2020 USD ($)
Guarantor Obligations [Line Items]
Guarantor obligations, maximum exposure, undiscounted	$ 255,500,000
Fixed maximum amounts guaranteed by year 2020	23,800,000
Fixed maximum amounts guaranteed by year 2021	199,700,000
Fixed maximum amounts guaranteed by year 2022	16,100,000
Fixed maximum amounts guaranteed by year 2023	5,300,000
Fixed maximum amounts guaranteed by year 2024	500,000
Fixed maximum amounts guaranteed, thereafter	1,100,000
No scheduled maturity date	9,000,000.0
Amount outstanding under guarantees that is reflected on balance sheet	0
Letters of credit	22,500,000
Letters of credit set to expire - 2020	20,200,000
Letters of credit set to expire - 2021	1,800,000
Letters of credit set to expire - 2022	500,000
Outstanding letters of credit	0
Amount of surety bonds outstanding	$ 922,700,000