Derivative Financial Instruments - Narrative (Details) - Derivatives designated as hedging instruments	3 Months Ended	9 Months Ended	12 Months Ended
	Sep. 30, 2018 agreement	Jun. 30, 2019 USD ($)	Sep. 30, 2018 USD ($)
Interest rate swap agreements | Designated as cash flow hedges
Derivative Financial Instruments
Number of derivative agreements | agreement	5
Notional amount		$ 240,600,000
Fixed rate		2.79%
Effective portion of interest rate swap agreements		$ (9,800,000)	$ 1,300,000
Gain (loss) to be reclassified during next twelve months		2,200,000
Foreign currency forward contracts and interest rate swap agreements
Derivative Financial Instruments
Effective portion of interest rate swap agreements		11,100,000
Ineffective portion of derivative instruments		0	0
Amounts excluded from effectiveness testing		$ 0	$ 0