Derivatives and Hedging Derivative Instruments and Hedging Activities Disclosure (Details) - USD ($) $ in Thousands	6 Months Ended
	Sep. 30, 2018	Mar. 31, 2019	Mar. 31, 2018
Other Assets [Member]
Derivative
Amount Net for Fair Value of Derivative Assets and (Liabilities)		$ 4,183	$ 4,904
Other Liabilities [Member]
Derivative
Amount Net for Fair Value of Derivative Assets and (Liabilities)		7,579	$ 6,446
Foreign Exchange Forward [Member]
Derivative
Derivative, Notional Amount		408,841
Derivative, Average Remaining Maturity	7 months
Future [Member]
Derivative
Derivative, Notional Amount		128,065
Derivative, Average Remaining Maturity	3 months
Total Return Swap Expiring in May 2019_2 [Member]
Derivative
Derivative, Fixed Interest Rate	1.60%
Total Return Swap Expiring in July 2019 [Member]
Derivative
Derivative, Fixed Interest Rate	1.60%
Total Return Swap [Member]
Derivative
Derivative, Notional Amount		61,230
Derivative Financial Instruments, Assets [Member] | Future [Member]
Derivative
Derivative, Notional Amount		$ 37,027