Goodwill and Other Intangible Assets - Gross Cost and Accumulated Amortization of Other Intangible Assets (Detail) - USD ($) $ in Thousands |
Dec. 31, 2015 |
Dec. 31, 2014 |
|---|---|---|
| Finite-Lived Intangible Assets [Line Items] | ||
| Other intangible assets, Gross Cost | $ 63,776 | $ 63,790 |
| Other intangible assets, Accumulated Amortization | 57,561 | 51,754 |
| Other intangible assets, Net Carrying Amount | 6,215 | 12,036 |
| Performance Fees [Member] | ||
| Finite-Lived Intangible Assets [Line Items] | ||
| Other intangible assets, Gross Cost | 30,740 | 30,740 |
| Other intangible assets, Accumulated Amortization | 25,192 | 21,116 |
| Other intangible assets, Net Carrying Amount | 5,548 | 9,624 |
| Management Fees, Customer Relationships and Non-Compete Agreements [Member] | ||
| Finite-Lived Intangible Assets [Line Items] | ||
| Other intangible assets, Gross Cost | 33,036 | 33,050 |
| Other intangible assets, Accumulated Amortization | 32,369 | 30,638 |
| Other intangible assets, Net Carrying Amount | $ 667 | $ 2,412 |