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 |
12 Months Ended | ||
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Dec. 31, 2017 |
Dec. 31, 2016 |
Dec. 31, 2015 |
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| Balance Sheet Related Disclosures [Abstract] | |||
| Increase (decrease) in the carrying value of the assets held in the rabbi trus | $ 849 | $ 470 | $ (57) |
| Increase (decrease) in the carrying value of the deferred compensation obligation | $ 904 | $ 452 | $ (67) |
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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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- References No definition available.
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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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