Derivative Financial Instruments - Offsetting Liabilities and Assets (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Sep. 30, 2015
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative financial assets, gross amount	$ 0	$ 41
Derivative financial liabilities, gross amount	(91,066)	(53,559)
Derivative financial assets (liabilities), gross amount	(91,066)	(53,518)
Derivative financial assets, amount offset	0	(41)
Derivative financial liabilities, amount offset	0	41
Derivative financial assets (liabilities), Net, amount offset	0	0
Derivative financial assets, net amount presented in Consolidated Balance Sheets	0	0
Derivative financial liabilities, net amount presented in Consolidated Balance Sheets	(91,066)	(53,518)
Derivative financial assets (liabilities), net amount presented in Consolidated Balance Sheets	(91,066)	(53,518)
Derivative financial assets, Held/pledged financial instruments	0	0
Derivative financial liabilities, Held/pledged financial instruments	91,066	53,518
Derivative liabilities (assets), Net, Held/pledged financial instruments	91,066	53,518
Derivative financial asset, net amount	0	0
Derivative financial liabilities, net amount	0	0
Derivative financial assets (liabilities), net, amount offset against collateral	$ 0	$ 0