Goodwill and Intangible Assets - Other Intangible Assets (Details) - USD ($) $ in Thousands	12 Months Ended
Sep. 30, 2018	Sep. 30, 2017
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	$ 8,195	$ 8,195
Accumulated amortization	(3,390)	(2,746)
Total	4,805	5,449
Additions during the year	0	4,796
Amortization during the year	$ 644	219
Wells Federal \| Core deposit intangible
Finite-Lived Intangible Assets [Line Items]
Additions during the year		4,178
Wells Federal \| Customer relationships
Finite-Lived Intangible Assets [Line Items]
Additions during the year		$ 618

The aggregate expense charged against earnings to allocate the cost of intangible assets (nonphysical assets not used in production) in a systematic and rational manner to the periods expected to benefit from such assets. As a noncash expense, this element is added back to net income when calculating cash provided by or used in operations using the indirect method.

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Amount before amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

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