Accounts Receivable, Net - Additional Information (Detail) - USD ($) $ in Millions |
Dec. 31, 2016 |
Dec. 31, 2015 |
|---|---|---|
| Accounts, Notes, Loans and Financing Receivable [Line Items] | ||
| Unbilled accounts receivable | $ 50.9 | $ 47.8 |
| Other Assets, Net | ||
| Accounts, Notes, Loans and Financing Receivable [Line Items] | ||
| Notes receivable, net of allowance (less than $0.1 million in December 31, 2016) | $ 0.1 | $ 0.5 |