| Selected Balance Sheet Data - Summary of Net Change in Carrying Value of Assets Held in Rabbi Trust and Deferred Compensation Liability (Detail) - USD ($) $ in Thousands | 3 Months Ended | 6 Months Ended | ||
|---|---|---|---|---|
| Jun. 30, 2016 | Jun. 30, 2015 | Jun. 30, 2016 | Jun. 30, 2015 | |
| Balance Sheet Related Disclosures [Abstract] | ||||
| Increase (decrease) in the carrying value of the assets held in the rabbi trust | $ 150 | $ (104) | $ 184 | $ 11 | 
| Increase (decrease) in the carrying value of the deferred compensation obligation | $ 151 | $ (94) | $ 188 | $ 59 | 
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- Definition The amount of increase or decrease in the fair value of plan assets during the reporting period. No definition available. 
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| X | ||||||||||
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- References No definition available. 
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| X | ||||||||||
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- Definition The increase (decrease) during the reporting period in the obligation created by employee agreements whereby earned compensation will be paid in the future. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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