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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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Effects of New Accounting Pronouncement or Change in Accounting Principle

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Percentage of domestic federal statutory tax rate applicable to pretax income (loss).

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-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
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