Fair Value Measurements (Fair Value Of Assets On Recurring Basis) (Details) (USD $) | Oct. 31, 2014 | Apr. 30, 2014 |
In Thousands, unless otherwise specified |
Fair Value Measurements Level 1 [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Total assets at fair value | $53,483 | $40,081 |
Fair Value Measurements Level 2 [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Total assets at fair value | 0 | 0 |
Fair Value Measurements Level 3 [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Total assets at fair value | 0 | 0 |
Money Market Funds [Member] | Fair Value Measurements Level 1 [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Total assets at fair value | 30,480 | 38,877 |
Money Market Funds [Member] | Fair Value Measurements Level 2 [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Total assets at fair value | 0 | 0 |
Money Market Funds [Member] | Fair Value Measurements Level 3 [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Total assets at fair value | 0 | 0 |
Mutual Funds [Member] | Fair Value Measurements Level 1 [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Total assets at fair value | 1,253 | 1,204 |
Mutual Funds [Member] | Fair Value Measurements Level 2 [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Total assets at fair value | 0 | 0 |
Mutual Funds [Member] | Fair Value Measurements Level 3 [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Total assets at fair value | 0 | 0 |
Certificates of Deposit [Member] | Fair Value Measurements Level 1 [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Total assets at fair value | 21,750 | ' |
Certificates of Deposit [Member] | Fair Value Measurements Level 2 [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Total assets at fair value | 0 | ' |
Certificates of Deposit [Member] | Fair Value Measurements Level 3 [Member] | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' |
Total assets at fair value | $0 | ' |