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Investments - Carrying Value and Amortized Cost of Company's Investments Summarized by Major Security Type (Parenthetical) (Detail) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2021	Dec. 31, 2020
Corporate debt securities | Maximum
Schedule of Available-for-sale Securities [Line Items]
Unrealized loss on securities	$ 500	$ 500

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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- Definition

The increase (decrease), resulting in a loss, in the difference between the fair value and the carrying value, or in the comparative fair values, of securities held at each balance sheet date, that was included in earnings for the period.

+ References

No definition available.

+ Details

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- Details

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- Details

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