Low Income Housing Partnerships (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017
Investments in Affordable Housing Projects [Abstract]
Investment In affordable housing limited partnerships	$ 82,600	$ 74,500
Obligations related to investments in affordable housing limited partnerships	$ 40,000	34,000
Affordable housing tax credits commitment, year to be paid	2021
Proportional amortization expense, amount	$ 6,800	7,000	$ 4,400
Affordable housing tax credits, amount	8,600	7,500	6,900
Net income tax benefit, low income housing partnerships	1,800	500	2,500
Impairment losses from the forfeiture or ineligibility of tax credits or other circumstances, amount	$ 0	$ 0	$ 0