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Restricted Shares Issued in Conjunction with Stock Plan (Detail) - Restricted Stock $ in Millions | 12 Months Ended
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Dec. 31, 2020 USD ($) shares
Period 1 |
Class of Stock [Line Items] |
Issuance Date | Jan. 29, 2018
Shares | shares | 37,510
Aggregate Market Value | $ | $ 1.6
Period 2 |
Class of Stock [Line Items] |
Issuance Date | Jan. 29, 2019
Shares | shares | 33,150
Aggregate Market Value | $ | $ 1.6
Period 3 |
Class of Stock [Line Items] |
Issuance Date | Jan. 28, 2020
Shares | shares | 28,630
Aggregate Market Value | $ | $ 1.8
Period 4 |
Class of Stock [Line Items] |
Issuance Date | Jul. 28, 2020
Shares | shares | 3,000
Aggregate Market Value | $ | $ 0.1

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