Soft Dollar Arrangements - Additional Information (Detail) - USD ($) $ in Thousands |
3 Months Ended | |
|---|---|---|
Mar. 31, 2018 |
Mar. 31, 2017 |
|
| Soft Dollar Arrangements [Abstract] | ||
| Soft dollar credits | $ 193 | $ 178 |
| X | ||||||||||
- Definition Soft dollar arrangements. No definition available.
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| X | ||||||||||
- Definition Soft dollar credits. No definition available.
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