Retirement Savings Plan (Details) - USD ($) $ in Thousands		12 Months Ended
	Jan. 01, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Defined Contribution Plan Disclosure [Line Items]
Employer contribution matching percentage		3.00%
Employee vesting period in the retirement saving plan		3 years
Company defined contribution plan		$ 647	$ 764	$ 682
Subsequent Event
Defined Contribution Plan Disclosure [Line Items]
Employer contribution matching percentage	3.00%
Employee vesting period in the retirement saving plan	2 years