| Goodwill - Summary of Changes to Carrying Amount of Goodwill (Detail) - USD ($) $ in Thousands | 9 Months Ended | 12 Months Ended | 
|---|---|---|
| Sep. 30, 2016 | Dec. 31, 2015 | |
| Goodwill [Line Items] | ||
| Beginning, Gross balance | $ 42,097 | $ 37,423 | 
| Beginning, Accumulated impairment losses | (17,415) | (17,415) | 
| Beginning, Net balance | 24,682 | 20,008 | 
| Ending, Gross balance | 42,583 | 42,097 | 
| Ending, Accumulated impairment losses | (17,415) | (17,415) | 
| Ending, Net balance | 25,168 | 24,682 | 
| Jamison | ||
| Goodwill [Line Items] | ||
| Goodwill, Acquisition | $ 4,674 | |
| Ending, Net balance | 4,674 | |
| Cappiccille | ||
| Goodwill [Line Items] | ||
| Goodwill, Acquisition | $ 486 | 
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- Definition Amount of increase in asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized resulting from a business combination. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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- Definition Amount before accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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- Definition Amount of accumulated impairment loss for an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. No definition available. 
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