Goodwill and Intangible Assets - Intangible Assets and Accumulated Amortization Balances (Detail) - USD ($) $ in Thousands |
Sep. 30, 2016 |
Dec. 31, 2015 |
|---|---|---|
| Acquired Finite-Lived Intangible Assets [Line Items] | ||
| Gross Carrying Amount | $ 166,121 | $ 140,429 |
| Accumulated Amortization | (80,173) | (69,727) |
| Net Carrying Amount | 85,948 | 70,702 |
| Customer relationships [Member] | ||
| Acquired Finite-Lived Intangible Assets [Line Items] | ||
| Gross Carrying Amount | 135,482 | 115,285 |
| Accumulated Amortization | (70,075) | (61,375) |
| Net Carrying Amount | 65,407 | 53,910 |
| Developed technology [Member] | ||
| Acquired Finite-Lived Intangible Assets [Line Items] | ||
| Gross Carrying Amount | 8,971 | 8,854 |
| Accumulated Amortization | (8,449) | (7,673) |
| Net Carrying Amount | 522 | 1,181 |
| Other [Member] | ||
| Acquired Finite-Lived Intangible Assets [Line Items] | ||
| Gross Carrying Amount | 21,668 | 16,290 |
| Accumulated Amortization | (1,649) | (679) |
| Net Carrying Amount | $ 20,019 | $ 15,611 |