Fair Value of Financial Instruments - Financial Instruments Not Measured at Fair Value on a Recurring Basis (Details) - Recurring - 2033 Notes - USD ($) $ in Thousands |
Jan. 31, 2016 |
May. 03, 2015 |
|---|---|---|
| Carrying Amount | ||
| Debt Instrument | ||
| Convertible notes | $ 228,561 | $ 221,406 |
| Fair Value | ||
| Debt Instrument | ||
| Convertible notes | 237,403 | 264,364 |
| Level 1 | Fair Value | ||
| Debt Instrument | ||
| Convertible notes | 237,403 | 264,364 |
| Level 2 | Fair Value | ||
| Debt Instrument | ||
| Convertible notes | 0 | 0 |
| Level 3 | Fair Value | ||
| Debt Instrument | ||
| Convertible notes | $ 0 | $ 0 |