Long-Term Incentive Plans - Additional Information (Detail) $ / shares in Units, $ in Millions	3 Months Ended
Mar. 31, 2021 USD ($) $ / shares
TSUs [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unrecognized compensation cost	$ 0.2
Weighted-average period of unrecognized compensation cost	1 year 2 months 12 days
PSUs [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Weighted-average period of unrecognized compensation cost	1 year 4 months 24 days
Decrease in share targets \| $ / shares	$ 0.25
PSUs [Member] \| Market Vesting Date [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock units vesting percentage	50.00%
PSUs [Member] \| First Anniversary Market-Vesting Date [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock units vesting percentage	25.00%
PSUs [Member] \| Second Anniversary Market-Vesting Date [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock units vesting percentage	25.00%
PSUs [Member] \| Maximum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unrecognized compensation cost	$ 0.1
2017 Non-Employee Directors Compensation Plan [Member] \| Restricted Stock Units (RSUs) [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Weighted-average period of unrecognized compensation cost	1 year 1 month 6 days
2017 Non-Employee Directors Compensation Plan [Member] \| Maximum [Member] \| Restricted Stock Units (RSUs) [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unrecognized compensation cost	$ 0.1

Share-based compensation arrangement by share-based payment award, increase decrease in share targets.

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- Definition

Weighted-average period over which cost not yet recognized is expected to be recognized for award under share-based payment arrangement, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
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- Definition

Amount of cost to be recognized for nonvested award under share-based payment arrangement. Excludes share and unit options.

+ References

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- Definition

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+ References

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+ References

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