Fair Value Measurements - Additional Information (Detail) - USD ($) |
1 Months Ended | 3 Months Ended |
|---|---|---|
Jan. 31, 2017 |
Apr. 30, 2017 |
|
| Fair Value Measurements Disclosure [Line Items] | ||
| Fair value measurements of our financial assets and liabilities | $ 12,970,000 | $ 12,974,000 |
| Goodwill impairment charge | 23,500,000 | 23,500,000 |
| Loss on impairment of long-lived assets held for sale | 300,000 | |
| Loss on impairment | 500,000 | |
| Other-than-temporary impairment | $ 0 | |
| Maximum maturity of marketable securities | Three months or less | |
| Cash equivalents and marketable securities | 38,700,000 | $ 37,100,000 |
| Fair Value, Inputs, Level 3 [Member] | ||
| Fair Value Measurements Disclosure [Line Items] | ||
| Fair value measurements of our financial assets and liabilities | $ 0 | $ 0 |