Marketable Securities - Company's Marketable Securities Measured at Fair Value (Detail) (USD $) | Jun. 30, 2014 | Sep. 30, 2013 |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Total | $87,592,000 | $83,113,000 |
Equities [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Total | 18,944,000 | 12,634,000 |
Mutual Funds [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Total | 24,608,000 | 28,264,000 |
Exchange Traded Funds [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Total | 2,010,000 | 5,162,000 |
Corporate Bonds [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Total | ' | 17,376,000 |
Municipal Bonds [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Total | ' | 15,555,000 |
United States Treasury Bills [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Total | 40,000,000 | 2,000,000 |
Cash [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Total | 2,030,000 | 2,122,000 |
Level 1 [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Total | 87,592,000 | 50,182,000 |
Level 1 [Member] | Equities [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Total | 18,944,000 | 12,634,000 |
Level 1 [Member] | Mutual Funds [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Total | 24,608,000 | 28,264,000 |
Level 1 [Member] | Exchange Traded Funds [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Total | 2,010,000 | 5,162,000 |
Level 1 [Member] | Corporate Bonds [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Total | ' | ' |
Level 1 [Member] | Municipal Bonds [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Total | ' | ' |
Level 1 [Member] | United States Treasury Bills [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Total | 40,000,000 | 2,000,000 |
Level 1 [Member] | Cash [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Total | 2,030,000 | 2,122,000 |
Level 2 [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Total | 0 | 32,931,000 |
Level 2 [Member] | Equities [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Total | 0 | ' |
Level 2 [Member] | Mutual Funds [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Total | 0 | ' |
Level 2 [Member] | Exchange Traded Funds [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Total | 0 | ' |
Level 2 [Member] | Corporate Bonds [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Total | ' | 17,376,000 |
Level 2 [Member] | Municipal Bonds [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Total | ' | 15,555,000 |
Level 2 [Member] | United States Treasury Bills [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Total | 0 | ' |
Level 2 [Member] | Cash [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Total | 0 | ' |
Level 3 [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Total | 0 | 0 |
Level 3 [Member] | Equities [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Total | 0 | 0 |
Level 3 [Member] | Mutual Funds [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Total | 0 | 0 |
Level 3 [Member] | Exchange Traded Funds [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Total | 0 | 0 |
Level 3 [Member] | Corporate Bonds [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Total | ' | 0 |
Level 3 [Member] | Municipal Bonds [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Total | ' | 0 |
Level 3 [Member] | United States Treasury Bills [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Total | 0 | 0 |
Level 3 [Member] | Cash [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Total | $0 | $0 |