Reclassifications Out of Accumulated Other Comprehensive Income (Loss) to Statements of Operations (Parenthetical) (Detail) - USD ($) $ in Thousands |
3 Months Ended | 9 Months Ended | ||
---|---|---|---|---|
Sep. 30, 2018 |
Oct. 01, 2017 |
Sep. 30, 2018 |
Oct. 01, 2017 |
|
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items] | ||||
Reclassifications, tax | $ 35 | $ 105 | $ 59 | $ 288 |
Unrealized Gains (Losses) on Marketable Securities | ||||
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items] | ||||
Reclassifications, tax | 17 | 67 | 6 | 173 |
Amortization of Prior Service Credit | ||||
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items] | ||||
Reclassifications, tax | $ 18 | $ 38 | $ 53 | $ 115 |