Guarantees (Details 3)	Sep. 30, 2016 USD ($)
Guarantor Obligations [Line Items]
Guarantor obligations, maximum exposure, undiscounted	$ 110,000,000
Fixed maximum amounts guaranteed by year 2016	4,200,000
Fixed maximum amounts guaranteed by year 2017	30,300,000
Fixed maximum amounts guaranteed by year 2018	12,000,000
Fixed maximum amounts guaranteed by year 2019	59,500,000
No scheduled maturity date	4,000,000
Amount outstanding under guarantees that is reflected on balance sheet	0
Letters of credit	34,900,000
Letters of credit set to expire - 2016	2,900,000
Letters of credit set to expire - 2017	32,000,000
Outstanding letters of credit	0
Amount of surety bonds outstanding	560,700,000
Financial guarantee [Member]
Guarantor Obligations [Line Items]
Guarantor obligations, maximum exposure, undiscounted	$ 64,900,000