The Company and Summary of Significant Accounting Principles - Concentrations of Risk - Additional Information (Detail) - USD ($) $ in Millions |
3 Months Ended | 9 Months Ended | 12 Months Ended | ||
|---|---|---|---|---|---|
Sep. 30, 2017 |
Sep. 30, 2016 |
Sep. 30, 2017 |
Sep. 30, 2016 |
Dec. 31, 2016 |
|
| Concentration Risk [Line Items] | |||||
| Increase (decrease) deferred tax assets | $ 0.7 | ||||
| Customer Concentration Risk [Member] | Accounts Receivable [Member] | |||||
| Concentration Risk [Line Items] | |||||
| Concentration risk, percentage | 10.00% | 10.00% | |||
| Customer Concentration Risk [Member] | Revenue [Member] | |||||
| Concentration Risk [Line Items] | |||||
| Concentration risk, percentage | 10.00% | 10.00% | 10.00% | 10.00% | |