Fair Value Measurements (Details) - USD ($) $ in Millions | 12 Months Ended | |
Jul. 31, 2017 | Apr. 30, 2018 |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis | | |
Cash equivalents | $ 0 | $ 524.5 |
Short-term investments | 630.7 | 672.2 |
Prepaid expenses and other current assets | 0 | 1 |
Long-term investments | 789.3 | 592.9 |
Total assets measured at fair value | 1,420 | 1,790.6 |
Accrued and other liabilities | 0 | 2.3 |
Total liabilities measured at fair value | 0 | 2.3 |
Level 1 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis | | |
Cash equivalents | 0 | 361.8 |
Short-term investments | 0 | 0 |
Prepaid expenses and other current assets | 0 | 0 |
Long-term investments | 0 | 0 |
Total assets measured at fair value | 0 | 361.8 |
Accrued and other liabilities | 0 | 0 |
Total liabilities measured at fair value | 0 | 0 |
Level 2 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis | | |
Cash equivalents | 0 | 162.7 |
Short-term investments | 630.7 | 672.2 |
Prepaid expenses and other current assets | 0 | 1 |
Long-term investments | 789.3 | 592.9 |
Total assets measured at fair value | 1,420 | 1,428.8 |
Accrued and other liabilities | 0 | 2.3 |
Total liabilities measured at fair value | 0 | 2.3 |
Level 3 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis | | |
Cash equivalents | 0 | 0 |
Short-term investments | 0 | 0 |
Prepaid expenses and other current assets | 0 | 0 |
Long-term investments | 0 | 0 |
Total assets measured at fair value | 0 | 0 |
Accrued and other liabilities | 0 | 0 |
Total liabilities measured at fair value | 0 | 0 |
Money market funds | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis | | |
Cash equivalents | 0 | 361.8 |
Money market funds | Level 1 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis | | |
Cash equivalents | 0 | 361.8 |
Money market funds | Level 2 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis | | |
Cash equivalents | 0 | 0 |
Money market funds | Level 3 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis | | |
Cash equivalents | 0 | 0 |
Commercial paper | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis | | |
Cash equivalents | 0 | 32.1 |
Commercial paper | Level 1 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis | | |
Cash equivalents | 0 | 0 |
Commercial paper | Level 2 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis | | |
Cash equivalents | 0 | 32.1 |
Commercial paper | Level 3 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis | | |
Cash equivalents | 0 | 0 |
Corporate debt securities | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis | | |
Cash equivalents | 0 | 1 |
Short-term investments | 159.4 | 145.6 |
Long-term investments | 186.5 | 135.6 |
Corporate debt securities | Level 1 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis | | |
Cash equivalents | 0 | 0 |
Short-term investments | 0 | 0 |
Long-term investments | 0 | 0 |
Corporate debt securities | Level 2 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis | | |
Cash equivalents | 0 | 1 |
Short-term investments | 159.4 | 145.6 |
Long-term investments | 186.5 | 135.6 |
Corporate debt securities | Level 3 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis | | |
Cash equivalents | 0 | 0 |
Short-term investments | 0 | 0 |
Long-term investments | 0 | 0 |
U.S. government and agency securities | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis | | |
Cash equivalents | 0 | 129.6 |
Short-term investments | 471.3 | 521.2 |
Long-term investments | 597.4 | 457.3 |
U.S. government and agency securities | Level 1 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis | | |
Cash equivalents | 0 | 0 |
Short-term investments | 0 | 0 |
Long-term investments | 0 | 0 |
U.S. government and agency securities | Level 2 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis | | |
Cash equivalents | 0 | 129.6 |
Short-term investments | 471.3 | 521.2 |
Long-term investments | 597.4 | 457.3 |
U.S. government and agency securities | Level 3 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis | | |
Cash equivalents | 0 | 0 |
Short-term investments | 0 | 0 |
Long-term investments | 0 | 0 |
Certificates of deposit | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis | | |
Short-term investments | 0 | 5.4 |
Long-term investments | 5.4 | 0 |
Certificates of deposit | Level 1 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis | | |
Short-term investments | 0 | 0 |
Long-term investments | 0 | 0 |
Certificates of deposit | Level 2 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis | | |
Short-term investments | 0 | 5.4 |
Long-term investments | 5.4 | 0 |
Certificates of deposit | Level 3 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis | | |
Short-term investments | 0 | 0 |
Long-term investments | 0 | 0 |
Foreign currency forward contracts | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis | | |
Prepaid expenses and other current assets | 0 | 1 |
Accrued and other liabilities | 0 | 2.3 |
Foreign currency forward contracts | Level 1 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis | | |
Prepaid expenses and other current assets | 0 | 0 |
Accrued and other liabilities | 0 | 0 |
Foreign currency forward contracts | Level 2 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis | | |
Prepaid expenses and other current assets | 0 | 1 |
Accrued and other liabilities | 0 | 2.3 |
Foreign currency forward contracts | Level 3 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis | | |
Prepaid expenses and other current assets | 0 | 0 |
Accrued and other liabilities | 0 | $ 0 |
Fair Value, Measurements, Nonrecurring | Level 3 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis | | |
Leasehold improvements and other long-lived assets related to previous corporate headquarters | 4.2 | |
General and administrative | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis | | |
Impairment of property and equipment | $ 20.9 | |