Fair Value Measurements - Schedule of Assets Measured at Fair Value On Recurring Basis (Details) - Fair Value, Measurements, Recurring [Member] - USD ($)	Jan. 31, 2019	Apr. 30, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total fair value of assets measured on a recurring basis	$ 25,770,000	$ 26,346,000
Municipal Bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total fair value of assets measured on a recurring basis	5,464,000	5,741,000
Corporate Bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total fair value of assets measured on a recurring basis	57,000	131,000
REITs [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total fair value of assets measured on a recurring basis	87,000	106,000
Equity Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total fair value of assets measured on a recurring basis	18,986,000	19,333,000
Money Markets and CDs [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total fair value of assets measured on a recurring basis	1,176,000	1,035,000
Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total fair value of assets measured on a recurring basis	20,219,000	20,499,000
Level 1 [Member] | Municipal Bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total fair value of assets measured on a recurring basis
Level 1 [Member] | Corporate Bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total fair value of assets measured on a recurring basis	57,000	131,000
Level 1 [Member] | REITs [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total fair value of assets measured on a recurring basis
Level 1 [Member] | Equity Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total fair value of assets measured on a recurring basis	18,986,000	19,333,000
Level 1 [Member] | Money Markets and CDs [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total fair value of assets measured on a recurring basis	1,176,000	1,035,000
Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total fair value of assets measured on a recurring basis	5,551,000	5,847,000
Level 2 [Member] | Municipal Bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total fair value of assets measured on a recurring basis	5,464,000	5,741,000
Level 2 [Member] | Corporate Bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total fair value of assets measured on a recurring basis
Level 2 [Member] | REITs [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total fair value of assets measured on a recurring basis	87,000	106,000
Level 2 [Member] | Equity Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total fair value of assets measured on a recurring basis
Level 2 [Member] | Money Markets and CDs [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total fair value of assets measured on a recurring basis
Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total fair value of assets measured on a recurring basis
Level 3 [Member] | Municipal Bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total fair value of assets measured on a recurring basis
Level 3 [Member] | Corporate Bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total fair value of assets measured on a recurring basis
Level 3 [Member] | REITs [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total fair value of assets measured on a recurring basis
Level 3 [Member] | Equity Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total fair value of assets measured on a recurring basis
Level 3 [Member] | Money Markets and CDs [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total fair value of assets measured on a recurring basis