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Schedule II - Valuation and Qualifying Accounts (Detail) - USD ($) $ in Thousands | 12 Months Ended
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Dec. 31, 2018 | Dec. 31, 2017 | Dec. 31, 2016
Allowance for Doubtful Accounts [Member] |  |  |
Valuation and Qualifying Accounts Disclosure [Line Items] |  |  |
Balance at beginning of period |  |  | $ 19
Charged to costs & expenses | $ 128 |  |
Deductions |  |  | 19
Balance at end of period | 128 |  |
Inventory Reserve [Member] |  |  |
Valuation and Qualifying Accounts Disclosure [Line Items] |  |  |
Balance at beginning of period | 23,355 | $ 25,249 | 26,675
Charged to costs & expenses | 7,006 | 6,406 | 3,303
Deductions | 352 | 8,300 | 4,729
Balance at end of period | 30,009 | 23,355 | 25,249
Warranty Liability [Member] |  |  |
Valuation and Qualifying Accounts Disclosure [Line Items] |  |  |
Balance at beginning of period | 9,724 | 8,548 | 8,739
Charged to costs & expenses | 7,392 | 6,951 | 8,561
Deductions | 8,493 | 5,775 | 8,752
Balance at end of period | 8,623 | 9,724 | 8,548
Deferred Tax Asset Valuation Allowance [Member] |  |  |
Valuation and Qualifying Accounts Disclosure [Line Items] |  |  |
Balance at beginning of period | 6,006 | 6,149 | 7,250
Charged to costs & expenses |  | 18 | 69
Deductions | 190 | 161 | 1,170
Balance at end of period | $ 5,816 | $ 6,006 | $ 6,149

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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) -URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e24092-122690 + Details
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