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Derivatives and Hedging Activities (Details) - USD ($) | 6 Months Ended |
--- | --- | ---
Mar. 31, 2016 | Sep. 30, 2015
Derivative [Line Items] |  |
Gain (loss) on derivative instruments | $ 0 |
Derivative asset, fair value, gross asset | 17,498,000 | $ 11,879,000
Derivative liability, fair value, gross liability | 45,069,000 | 27,400,000
Interest rate swap agreements |  |
Derivative [Line Items] |  |
Customer derivatives program | 525,465,000 | 439,416,000
Notional amount | 54,155,000 | 54,815,000
Interest rate contracts | Other assets |  |
Derivative [Line Items] |  |
Derivative asset, fair value, gross asset | 17,498,000 | 11,879,000
Interest rate contracts | Other liabilities |  |
Derivative [Line Items] |  |
Derivative liability, fair value, gross liability | 17,498,000 | 11,879,000
Commercial loan hedge | Other assets |  |
Derivative [Line Items] |  |
Derivative asset, fair value, gross asset | 0 | 0
Commercial loan hedge | Other liabilities |  |
Derivative [Line Items] |  |
Derivative liability, fair value, gross liability | 2,329,000 | 966,000
Long term borrowing hedge | Other assets |  |
Derivative [Line Items] |  |
Derivative asset, fair value, gross asset | 0 | 0
Long term borrowing hedge | Other liabilities |  |
Derivative [Line Items] |  |
Derivative liability, fair value, gross liability | 25,242,000 | 14,555,000
Forward Contracts | Interest rate swap agreements |  |
Derivative [Line Items] |  |
Notional amount | $ 600,000,000 | $ 400,000,000

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