Fair value of financial instruments (Details) (USD $) | 9 Months Ended | |
Mar. 31, 2014 | Mar. 31, 2013 | Jun. 30, 2013 |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' | ' |
Estimated Fair Value | $146,002,000 | ' | $191,685,000 |
Amortization of net premium on short-term investments | 2,720,000 | 3,269,000 | ' |
Financial liabilities measured at fair value on a recurring basis | 0 | ' | 0 |
Short-term investments | ' | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' | ' |
Estimated Fair Value | 130,651,000 | ' | 165,898,000 |
Short-term investments | Certificates of deposit | ' | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' | ' |
Estimated Fair Value | 0 | ' | 1,003,000 |
Short-term investments | Municipal securities | ' | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' | ' |
Estimated Fair Value | 104,753,000 | ' | 148,993,000 |
Short-term investments | Commercial paper | ' | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' | ' |
Estimated Fair Value | 1,997,000 | ' | 3,391,000 |
Short-term investments | Corporate bonds | ' | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' | ' |
Estimated Fair Value | 23,901,000 | ' | 12,511,000 |
Total | ' | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' | ' |
Estimated Fair Value | 132,687,000 | ' | 168,139,000 |
Total | Short-term investments | ' | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' | ' |
Estimated Fair Value | 130,651,000 | ' | 165,898,000 |
Total | Short-term investments | Certificates of deposit | ' | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' | ' |
Estimated Fair Value | 0 | ' | 1,003,000 |
Total | Short-term investments | Municipal securities | ' | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' | ' |
Estimated Fair Value | 104,753,000 | ' | 148,993,000 |
Total | Short-term investments | Commercial paper | ' | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' | ' |
Estimated Fair Value | 1,997,000 | ' | 3,391,000 |
Total | Short-term investments | Corporate bonds | ' | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' | ' |
Estimated Fair Value | 23,901,000 | ' | 12,511,000 |
Total | Cash equivalents | ' | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' | ' |
Estimated Fair Value | 2,036,000 | ' | 2,241,000 |
Total | Cash equivalents | Money market mutual funds | ' | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' | ' |
Estimated Fair Value | 1,036,000 | ' | 2,241,000 |
Total | Cash equivalents | Commercial paper | ' | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' | ' |
Estimated Fair Value | 1,000,000 | ' | ' |
Quoted Prices in Active Markets for Identical Assets (Level 1) | ' | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' | ' |
Estimated Fair Value | 1,036,000 | ' | 2,241,000 |
Quoted Prices in Active Markets for Identical Assets (Level 1) | Short-term investments | ' | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' | ' |
Estimated Fair Value | 0 | ' | 0 |
Quoted Prices in Active Markets for Identical Assets (Level 1) | Short-term investments | Certificates of deposit | ' | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' | ' |
Estimated Fair Value | 0 | ' | 0 |
Quoted Prices in Active Markets for Identical Assets (Level 1) | Short-term investments | Municipal securities | ' | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' | ' |
Estimated Fair Value | 0 | ' | 0 |
Quoted Prices in Active Markets for Identical Assets (Level 1) | Short-term investments | Commercial paper | ' | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' | ' |
Estimated Fair Value | 0 | ' | 0 |
Quoted Prices in Active Markets for Identical Assets (Level 1) | Short-term investments | Corporate bonds | ' | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' | ' |
Estimated Fair Value | 0 | ' | 0 |
Quoted Prices in Active Markets for Identical Assets (Level 1) | Cash equivalents | ' | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' | ' |
Estimated Fair Value | 1,036,000 | ' | 2,241,000 |
Quoted Prices in Active Markets for Identical Assets (Level 1) | Cash equivalents | Money market mutual funds | ' | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' | ' |
Estimated Fair Value | 1,036,000 | ' | 2,241,000 |
Quoted Prices in Active Markets for Identical Assets (Level 1) | Cash equivalents | Commercial paper | ' | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' | ' |
Estimated Fair Value | 0 | ' | ' |
Significant Other Observable Inputs (Level 2) | ' | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' | ' |
Estimated Fair Value | 131,651,000 | ' | 165,898,000 |
Significant Other Observable Inputs (Level 2) | Short-term investments | ' | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' | ' |
Estimated Fair Value | 130,651,000 | ' | 165,898,000 |
Significant Other Observable Inputs (Level 2) | Short-term investments | Certificates of deposit | ' | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' | ' |
Estimated Fair Value | 0 | ' | 1,003,000 |
Significant Other Observable Inputs (Level 2) | Short-term investments | Municipal securities | ' | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' | ' |
Estimated Fair Value | 104,753,000 | ' | 148,993,000 |
Significant Other Observable Inputs (Level 2) | Short-term investments | Commercial paper | ' | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' | ' |
Estimated Fair Value | 1,997,000 | ' | 3,391,000 |
Significant Other Observable Inputs (Level 2) | Short-term investments | Corporate bonds | ' | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' | ' |
Estimated Fair Value | 23,901,000 | ' | 12,511,000 |
Significant Other Observable Inputs (Level 2) | Cash equivalents | ' | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' | ' |
Estimated Fair Value | 1,000,000 | ' | 0 |
Significant Other Observable Inputs (Level 2) | Cash equivalents | Money market mutual funds | ' | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' | ' |
Estimated Fair Value | 0 | ' | 0 |
Significant Other Observable Inputs (Level 2) | Cash equivalents | Commercial paper | ' | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' | ' |
Estimated Fair Value | 1,000,000 | ' | ' |
Significant Unobservable Inputs (Level 3) | ' | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' | ' |
Estimated Fair Value | 0 | ' | 0 |
Significant Unobservable Inputs (Level 3) | Short-term investments | ' | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' | ' |
Estimated Fair Value | 0 | ' | 0 |
Significant Unobservable Inputs (Level 3) | Short-term investments | Certificates of deposit | ' | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' | ' |
Estimated Fair Value | 0 | ' | 0 |
Significant Unobservable Inputs (Level 3) | Short-term investments | Municipal securities | ' | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' | ' |
Estimated Fair Value | 0 | ' | 0 |
Significant Unobservable Inputs (Level 3) | Short-term investments | Commercial paper | ' | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' | ' |
Estimated Fair Value | 0 | ' | 0 |
Significant Unobservable Inputs (Level 3) | Short-term investments | Corporate bonds | ' | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' | ' |
Estimated Fair Value | 0 | ' | 0 |
Significant Unobservable Inputs (Level 3) | Cash equivalents | ' | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' | ' |
Estimated Fair Value | 0 | ' | 0 |
Significant Unobservable Inputs (Level 3) | Cash equivalents | Money market mutual funds | ' | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' | ' |
Estimated Fair Value | 0 | ' | 0 |
Significant Unobservable Inputs (Level 3) | Cash equivalents | Commercial paper | ' | ' | ' |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ' | ' | ' |
Estimated Fair Value | $0 | ' | ' |