Adoption of Accounting Standards Codification 842 - Balance Sheet (Details) - USD ($) $ in Thousands	Sep. 28, 2019	Jan. 01, 2019	Dec. 31, 2018
Assets
Other current assets	$ 5,947	$ 6,323	$ 6,531
Operating lease right-of-use assets	18,602	18,985
Non-current deferred income taxes	313	313	308
Other assets	5,290	5,409	5,155
Liabilities
Operating lease liabilities	2,915	2,544
Accrued and other liabilities	37,701	37,457	37,786
Non-current operating lease liabilities	17,156	18,117
Non-current deferred income taxes	18,107	17,994	18,070
Other long-term liabilities	14,855	13,485	14,441
Shareholders’ Equity
Retained earnings	$ 203,682	180,092	$ 180,356
Accounting Standards Update 2016-02
Assets
Other current assets		(208)
Operating lease right-of-use assets		18,985
Non-current deferred income taxes		5
Other assets		254
Liabilities
Operating lease liabilities		2,544
Accrued and other liabilities		(329)
Non-current operating lease liabilities		18,117
Non-current deferred income taxes		(76)
Other long-term liabilities		(956)
Shareholders’ Equity
Retained earnings		$ (264)