Investment Securities and Fair Value Measurements - Fair Value Measurements (Details) - USD ($) $ in Thousands | May. 06, 2015 | Sep. 30, 2015 | Sep. 30, 2014 | Sep. 30, 2015 | Sep. 30, 2014 | Dec. 31, 2014 |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | | | |
Available-for-sale Securities | | $ 51,855 | | $ 51,855 | | |
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] | | | | | | |
Payment of contingent consideration | $ 2,400 | | | 2,429 | $ 0 | |
Contingent Consideration | | | | | | |
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] | | | | | | |
Fair value, at beginning of period | | 0 | $ 2,407 | 2,429 | 2,403 | |
Change in fair value recorded in general and administrative expenses | | 0 | (60) | 0 | (56) | |
Payment of contingent consideration | | 0 | 0 | (2,429) | 0 | |
Fair value, at end of period | | 0 | $ 2,347 | 0 | $ 2,347 | |
Fair Value, Measurements, Recurring | | | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | | | |
Total Assets | | 58,649 | | 58,649 | | $ 3,696 |
Contingent consideration | | | | | | 2,429 |
Total Liabilities | | | | | | 2,429 |
Fair Value, Measurements, Recurring | Level 1 | | | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | | | |
Total Assets | | 12,772 | | 12,772 | | 3,696 |
Contingent consideration | | | | | | 0 |
Total Liabilities | | | | | | 0 |
Fair Value, Measurements, Recurring | Level 2 | | | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | | | |
Total Assets | | 45,877 | | 45,877 | | 0 |
Contingent consideration | | | | | | 0 |
Total Liabilities | | | | | | 0 |
Fair Value, Measurements, Recurring | Level 3 | | | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | | | |
Total Assets | | 0 | | 0 | | 0 |
Contingent consideration | | | | | | 2,429 |
Total Liabilities | | | | | | 2,429 |
Certificates of Deposit | | | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | | | |
Available-for-sale Securities | | 5,978 | | 5,978 | | |
Certificates of Deposit | Fair Value, Measurements, Recurring | | | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | | | |
Available-for-sale Securities | | 5,978 | | 5,978 | | |
Certificates of Deposit | Fair Value, Measurements, Recurring | Level 1 | | | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | | | |
Available-for-sale Securities | | 5,978 | | 5,978 | | |
Certificates of Deposit | Fair Value, Measurements, Recurring | Level 2 | | | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | | | |
Available-for-sale Securities | | 0 | | 0 | | |
Certificates of Deposit | Fair Value, Measurements, Recurring | Level 3 | | | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | | | |
Available-for-sale Securities | | 0 | | 0 | | |
Agency Securities | | | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | | | |
Available-for-sale Securities | | 11,008 | | 11,008 | | |
Agency Securities | Fair Value, Measurements, Recurring | | | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | | | |
Available-for-sale Securities | | 11,008 | | 11,008 | | |
Agency Securities | Fair Value, Measurements, Recurring | Level 1 | | | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | | | |
Available-for-sale Securities | | 0 | | 0 | | |
Agency Securities | Fair Value, Measurements, Recurring | Level 2 | | | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | | | |
Available-for-sale Securities | | 11,008 | | 11,008 | | |
Agency Securities | Fair Value, Measurements, Recurring | Level 3 | | | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | | | |
Available-for-sale Securities | | 0 | | 0 | | |
Corporate Bonds | | | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | | | |
Available-for-sale Securities | | 34,869 | | 34,869 | | |
Corporate Bonds | Fair Value, Measurements, Recurring | | | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | | | |
Available-for-sale Securities | | 34,869 | | 34,869 | | |
Corporate Bonds | Fair Value, Measurements, Recurring | Level 1 | | | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | | | |
Available-for-sale Securities | | 0 | | 0 | | |
Corporate Bonds | Fair Value, Measurements, Recurring | Level 2 | | | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | | | |
Available-for-sale Securities | | 34,869 | | 34,869 | | |
Corporate Bonds | Fair Value, Measurements, Recurring | Level 3 | | | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | | | |
Available-for-sale Securities | | 0 | | 0 | | |
Money Market Accounts | Fair Value, Measurements, Recurring | | | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | | | |
Cash equivalents | | 6,668 | | 6,668 | | 3,696 |
Money Market Accounts | Fair Value, Measurements, Recurring | Level 1 | | | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | | | |
Cash equivalents | | 6,668 | | 6,668 | | 3,696 |
Money Market Accounts | Fair Value, Measurements, Recurring | Level 2 | | | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | | | |
Cash equivalents | | 0 | | 0 | | 0 |
Money Market Accounts | Fair Value, Measurements, Recurring | Level 3 | | | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | | | |
Cash equivalents | | 0 | | 0 | | $ 0 |
Mutual Funds | Fair Value, Measurements, Recurring | | | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | | | |
Cash equivalents | | 126 | | 126 | | |
Mutual Funds | Fair Value, Measurements, Recurring | Level 1 | | | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | | | |
Cash equivalents | | 126 | | 126 | | |
Mutual Funds | Fair Value, Measurements, Recurring | Level 2 | | | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | | | |
Cash equivalents | | 0 | | 0 | | |
Mutual Funds | Fair Value, Measurements, Recurring | Level 3 | | | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | | | |
Cash equivalents | | $ 0 | | $ 0 | | |