Fair Value Measurements - Fair Value Assets and Liabilities Measured on Recurring Basis (Detail) - Fair Value, Measurements, Recurring - USD ($) $ in Thousands |
Mar. 31, 2019 |
Dec. 31, 2018 |
Mar. 31, 2018 |
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Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] | ||||||
Non-qualified savings plan assets | [1] | $ 2,683 | $ 2,052 | $ 2,079 | ||
Total | 2,683 | 2,052 | 2,079 | |||
Level 1 | ||||||
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] | ||||||
Non-qualified savings plan assets | [1] | 2,683 | 2,052 | 2,079 | ||
Total | $ 2,683 | $ 2,052 | $ 2,079 | |||
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