Recent Accounting Pronouncements - Additional Information (Detail) $ in Thousands	6 Months Ended
	Mar. 31, 2018 USD ($)
ASU 2016-02, Leases [Member] | Maximum [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Estimated percentage increase in assets from recognition of leases	1.00%
Estimated percentage increase in liabilities from recognition of leases	1.00%
ASU 2018-02 [Member] | New Accounting Pronouncement, Early Adoption, Effect [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Reclassification between accumulated other comprehensive income and retained earnings	$ 346,000