Investment in Historic Tax Credit Entity (Additional Information) (Detail) - USD ($)		3 Months Ended			9 Months Ended
	Oct. 15, 2014	Jun. 30, 2017	Mar. 31, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Sep. 30, 2016
Percentage Of Received Equity Interest	99.00%
Percentage Of Receive Operating Profit And Losses	99.00%
Investment Credit Available To Be Estimated	$ 4,700,000
Other Assets	$ 4,200,000	$ 4,777,000			$ 4,777,000		$ 3,956,000
Investment Tax Credit		$ 0		$ 4,309,000	$ 226,000	$ 4,309,000
Investment Tax Credit Percentage					90.00%
Historical Tax Credit On Investment			$ 5,000,000		$ 249,000	4,800,000
Increase In Equity Investment			$ 4,500,000
Investment In Credit [Member]
Other Liabilities							$ 118,000
Tax Credit Carryforward, Amount				4,800,000		$ 4,800,000
Investment Tax Credit				$ 4,300,000