Income Taxes - Components of Deferred Tax Assets and Liabilities (Detail) - USD ($) $ in Millions |
Dec. 31, 2016 |
Dec. 31, 2015 |
|---|---|---|
| Deferred tax assets: | ||
| Accrued expenses | $ 3.4 | $ 3.2 |
| Accounts receivable | 1.0 | 1.2 |
| Net operating loss carryforward | 116.7 | 123.6 |
| Stock-based compensation | 1.8 | 2.1 |
| Intangible assets | 8.0 | 8.0 |
| Credits | 1.0 | 1.0 |
| Property and equipment | 0.4 | 0.3 |
| Other | 2.5 | 2.9 |
| Deferred Tax Assets Gross | 134.8 | 142.3 |
| Valuation allowance | (1.2) | |
| Net deferred tax assets | 134.8 | 141.1 |
| Deferred tax liabilities: | ||
| Intangible assets | (89.6) | (82.5) |
| Deferred state taxes | (0.5) | (0.7) |
| Net deferred tax liabilities | (90.1) | (83.2) |
| Deferred Assets Liabilities Net | $ 44.7 | $ 57.9 |