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Employee Benefit Plans (Pension Benefit Plan) - Additional Information (Detail) - USD ($) $ in Millions | 12 Months Ended |
--- | --- | ---
Dec. 31, 2019 | Dec. 31, 2018
Defined Benefit Plan Disclosure [Line Items] |  |
Accumulated benefit obligation | $ 43.9 | $ 37.2
Estimated amortization from accumulated other comprehensive income (loss) into net periodic pension cost in 2020 | $ 0.8 |
Bond Funds [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Percentage of target allocation ranges by asset class | 50.00% |
Equity Funds [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Percentage of target allocation ranges by asset class | 40.00% |
Cash, Real Estate, and Managed Futures [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Percentage of target allocation ranges by asset class | 10.00% |
Minimum [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Threshold for unamortized gain losses | 10.00% |

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