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Employee Benefit Plans and Stock-based Compensation - Additional Information (Detail) - USD ($) | 3 Months Ended | 9 Months Ended | 12 Months Ended |
--- | --- | --- | --- | ---
Sep. 28, 2018 | Jun. 29, 2018 | Sep. 29, 2017 | Sep. 28, 2018 | Sep. 29, 2017 | Dec. 31, 2017 | Jan. 01, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |
Employee Service Share-based Compensation, Tax Benefit from Exercise of Stock Options | $ 0 |  | $ 0 | $ 0 | $ 0 |  |
Total stock-based compensation | 5,433,000 |  | $ 3,720,000 | 14,202,000 | 11,107,000 |  |
Defined Benefit Plan, Benefit Obligation | 5,100,000 |  |  | 5,100,000 |  | $ 5,000,000 |
Liability, Defined Benefit Pension Plan, Current | 100,000 |  |  | 100,000 |  |  |
Liability, Defined Benefit Pension Plan, Noncurrent | 5,000,000 |  |  | $ 5,000,000 |  |  |
Discretionary contributions of plan |  |  |  | 25.00% |  |  |
Percent of employees' gross pay eligible for matching |  |  |  | 4.00% |  |  |
Maximum contribution amount per participant |  |  |  | $ 1,000 |  |  |
Contributions in period |  |  |  | 259,000 | $ 326,000 |  |
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized | $ 10,900,000 |  |  | $ 10,900,000 |  |  |
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition |  |  |  | 1 year 7 months 6 days |  |  |
Dividends, Share-based Compensation, Cash |  |  |  | $ 0 |  |  |
Stock Option |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |
Common Stock, Capital Shares Reserved for Future Issuance | 4,500,000 |  |  | 4,500,000 |  |  |
Performance-based Restricted Stock Units [Member] |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period |  |  |  | 1,443,168 |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period |  |  |  | 1,343,168 |  |  |
Total stock-based compensation | $ 2,600,000 |  |  | $ 6,000,000 |  |  |
Employee Service Share-based Compensation, Nonvested Awards, Compensation Not yet Recognized, Stock Options | 200,000 |  |  | $ 200,000 |  |  |
Market-based awards [Member] |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period |  | 40,000 |  |  |  | 344,500 |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period |  |  |  | 0 |  |  |
Total stock-based compensation | $ 36,775 |  |  | $ 200,000 |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period |  | 18 months |  |  |  | 3 years |
Aggregate Grant Date Fair Value of Market-Based Restricted Stock Units |  |  |  | $ 1,300,000 |  |  |
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition |  |  |  | 1 year 3 months 18 days |  |  |
Employee Stock Purchase Plan |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Number of Additional Shares Authorized |  |  |  | 1,300,000 |  |  |
Common Stock, Capital Shares Reserved for Future Issuance | 1,300,000 |  |  | 1,300,000 |  |  |
Discount Percentage On Purchase Of Stock |  |  |  | 15.00% |  |  |
Equity Option [Member] |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |
Grants in Period, Number of Shares |  |  |  | 0 |  |  |
TVN [Member] |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |
Payment for Pension and Other Postretirement Benefits |  |  |  | $ 0 |  |  |
Director Option Plans 2002 [Member] |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Number of Additional Shares Authorized |  |  |  | 400,000 |  |  |
Accounting Standards Update 2016-09 [Member] |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |
Modified Retrospective Cumulative Effect Adjustment to Retained Earnings |  |  |  |  |  |  | $ 69,000
Call Option [Member] | Employee Stock Purchase Plan |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |
Percentage of fair market value of Common Stock to purchase shares |  |  |  | 85.00% |  |  |
Put Option [Member] | Employee Stock Purchase Plan |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |
Percentage of fair market value of Common Stock to purchase shares |  |  |  | 15.00% |  |  |

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