Leases - Summary of Changes in Consolidated Balance Sheet for Adoption of Topic 842 (Details) - USD ($) $ in Thousands	Sep. 29, 2019	Dec. 31, 2018	Dec. 30, 2018
Noncurrent assets:
Other assets	$ 5,521		$ 5,557
Right-of-use lease assets	71,344
Deferred income taxes	1,971		539
Current liabilities:
Current portion of lease liabilities	4,163
Long-term liabilities:
Long-term lease liabilities	76,954
Other long-term liabilities	149		6,995
Stockholders' equity:
Retained earnings	$ 23,058		$ 17,528
Accounting Standards Update 2016-02
Noncurrent assets:
Other assets		$ 5,408
Right-of-use lease assets		70,666
Deferred income taxes		973
Current liabilities:
Current portion of lease liabilities		3,707
Long-term liabilities:
Long-term lease liabilities		75,489
Other long-term liabilities		7
Stockholders' equity:
Retained earnings		16,271
Accounting Standards Update 2016-02 | Adjustments Due to the Adoption of Topic 842
Noncurrent assets:
Other assets		(149)
Right-of-use lease assets		70,666
Deferred income taxes		434
Current liabilities:
Current portion of lease liabilities		3,707
Long-term liabilities:
Long-term lease liabilities		75,489
Other long-term liabilities		(6,988)
Stockholders' equity:
Retained earnings		$ (1,257)