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Valuation and Qualifying Accounts (Detail) - USD ($) $ in Thousands | 12 Months Ended
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Dec. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2018
Allowance for Doubtful Accounts |  |  |
Valuation And Qualifying Accounts Disclosure [Line Items] |  |  |
Balance at Beginning of Period | $ 1,193 | $ 851 | $ 973
Charged to Costs and Expenses | 1,298 | 969 | 1,005
Charged to Other Accounts | 33 | (8) | (121)
Deductions from Reserves | (1,363) | (619) | (1,006)
Balance at End of Period | 1,161 | 1,193 | 851
Allowance for Deferred Income Tax Assets |  |  |
Valuation And Qualifying Accounts Disclosure [Line Items] |  |  |
Balance at Beginning of Period | 17,316 | 9,977 | 27,578
Charged to Costs and Expenses |  | 7,830 |
Charged to Other Accounts | 139 | (491) | (14,009)
Deductions from Reserves | (258) |  | (3,592)
Balance at End of Period | 17,197 | 17,316 | 9,977
Reserve for Inventory |  |  |
Valuation And Qualifying Accounts Disclosure [Line Items] |  |  |
Balance at Beginning of Period | 6,073 | 6,270 | 7,887
Charged to Costs and Expenses | 1,768 | 1,679 | 2,712
Charged to Other Accounts | 214 | (56) | (1,047)
Deductions from Reserves | (914) | (1,820) | (3,282)
Balance at End of Period | $ 7,141 | $ 6,073 | $ 6,270

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- Definition Amount of valuation and qualifying accounts and reserves. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 4 -Subparagraph (SX 210.12-09(Column B)) -URI http://asc.fasb.org/extlink&oid=120395691&loc=d3e24092-122690 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 4 -Subparagraph (SX 210.12-09(Column E)) -URI http://asc.fasb.org/extlink&oid=120395691&loc=d3e24092-122690 + Details
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