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Impact of Recent Accounting Pronouncements - Additional Information (Detail) - USD ($) $ in Millions | 3 Months Ended | 12 Months Ended
--- | --- | ---
Mar. 31, 2019 | Dec. 31, 2018
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent | 21.00% | 35.00%
Accounting Standards Update 2018-02 [Member] | Retained Earnings |  |
Effect of adopting | $ 2.5 |
Accounting Standards Update 2018-02 [Member] | Accumulated Other Comprehensive Loss |  |
Effect of adopting | $ 2.5 |

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