Nature of Operations and Summary of Significant Accounting Policies - Company's Assets Measured at Fair Value (Detail) - USD ($)	Sep. 30, 2017	Sep. 30, 2016
Investment Holdings [Line Items]
Total	$ 87,886,000	$ 85,938,000
Equities [Member]
Investment Holdings [Line Items]
Total	11,338,000	2,408,000
Mutual Funds [Member]
Investment Holdings [Line Items]
Total	7,155,000	5,212,000
Exchange Traded Funds [Member]
Investment Holdings [Line Items]
Total	3,417,000	510,000
Corporate Bonds [Member]
Investment Holdings [Line Items]
Total	7,196,000
Government Securities [Member]
Investment Holdings [Line Items]
Total	54,542,000	69,583,000
Cash and Money Funds [Member]
Investment Holdings [Line Items]
Total	4,238,000	8,225,000
Level 1 [Member]
Investment Holdings [Line Items]
Total	80,690,000	85,938,000
Level 1 [Member] | Equities [Member]
Investment Holdings [Line Items]
Total	11,338,000	2,408,000
Level 1 [Member] | Mutual Funds [Member]
Investment Holdings [Line Items]
Total	7,155,000	5,212,000
Level 1 [Member] | Exchange Traded Funds [Member]
Investment Holdings [Line Items]
Total	3,417,000	510,000
Level 1 [Member] | Government Securities [Member]
Investment Holdings [Line Items]
Total	54,542,000	69,583,000
Level 1 [Member] | Cash and Money Funds [Member]
Investment Holdings [Line Items]
Total	4,238,000	$ 8,225,000
Level 2 [Member]
Investment Holdings [Line Items]
Total	7,196,000
Level 2 [Member] | Corporate Bonds [Member]
Investment Holdings [Line Items]
Total	$ 7,196,000