Description of Business and Summary of Significant Accounting Policies - Condensed Consolidated Statements of Income (Details) - USD ($)
$ / shares in Units, $ in Thousands
3 Months Ended 9 Months Ended 12 Months Ended
Oct. 02, 2020
Jul. 03, 2020
Apr. 03, 2020
Dec. 31, 2019
Sep. 27, 2019
Jun. 28, 2019
Mar. 29, 2019
Oct. 02, 2020
Sep. 27, 2019
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
Error Corrections and Prior Period Adjustments Restatement [Line Items]                        
Revenue $ 352,415       $ 359,873     $ 1,040,212 $ 1,017,368      
Cost of revenue 320,234       327,523     951,743 923,671      
Operating income 14,837       12,416     29,751 34,000      
Income from operations before income taxes 13,898       10,509     25,763 29,189      
Income tax expense 3,507       2,668     5,593 6,657      
Net income $ 10,391 $ 1,111 $ 8,668   $ 7,841 $ 7,617 $ 7,074 $ 20,170 $ 22,532      
Earnings per share                        
Basic (in dollars per share) $ 0.89       $ 0.68     $ 1.74 $ 1.97      
Diluted (in dollars per share) $ 0.88       $ 0.67     $ 1.72 $ 1.95      
As Previously Reported                        
Error Corrections and Prior Period Adjustments Restatement [Line Items]                        
Revenue         $ 359,854       $ 1,017,371      
Cost of revenue         325,537       921,685      
Operating income         14,383       35,989      
Income from operations before income taxes         12,476       31,178      
Income tax expense         3,094       7,088      
Net income         $ 9,382 7,617 7,091   $ 24,090      
Earnings per share                        
Basic (in dollars per share)         $ 0.82       $ 2.11      
Diluted (in dollars per share)         $ 0.80       $ 2.08      
Correction                        
Error Corrections and Prior Period Adjustments Restatement [Line Items]                        
Revenue         $ 19       $ (3)      
Cost of revenue         1,986       1,986      
Operating income         (1,967)       (1,989)      
Income from operations before income taxes         (1,967)       (1,989)      
Income tax expense         (426)       (431)      
Net income         $ (1,541) $ 0 $ (17)   $ (1,558) $ (1,500)    
Earnings per share                        
Basic (in dollars per share)         $ (0.14)       $ (0.14)      
Diluted (in dollars per share)       $ (0.00) $ (0.13) $ (0.00) $ (0.00)   $ (0.13) $ (0.13) $ (0.02) $ (0.01)