Income Taxes - Provision for Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended									12 Months Ended
	Dec. 31, 2018	Sep. 28, 2018	Jun. 29, 2018	Mar. 30, 2018	Dec. 31, 2017	Dec. 31, 2017	Sep. 29, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Domestic and foreign components of income (loss) before income taxes are as follows:
Domestic										$ (1,119)	$ 591	$ (35,100)
Foreign										3,388	3,466	1,564
Income (loss) before income taxes	$ (958)	$ 1,395	$ 1,303	$ 529		$ 1,831	$ 299	$ 650	$ 1,277	2,269	4,057	(33,536)
Current Income Tax Expense (Benefit), Continuing Operations [Abstract]
Current U.S. federal										16	(570)	47
Current Foreign										1,937	1,458	1,533
Current U.S. state and local										107	116	101
Current Total current tax										2,060	1,004	1,681
Deferred tax:
Enactment of the Tax Cuts and Jobs Act					$ 1,700					1,700	1,704
Deferred U.S. federal										3,939	347	(584)
Deferred Foreign										(784)	(25)	28
Deferred U.S. state and local										(129)	221	(23)
Deferred income taxes										3,026	2,247	(579)
Total tax	4,301	307	363	115		2,250	259	216	526	5,086	3,251	1,102
Income Tax Expense (Benefit), Continuing Operations, Income Tax Reconciliation [Abstract]
Tax at statutory rate										476	1,379	(11,402)
State tax, net of federal benefit										(12)	212	47
Non-taxable income										(300)	(573)	(495)
Non-deductible expenses										607	971	13,465
Change in estimate primarily related to foreign taxes										(767)	(69)	46
Change in valuation allowance related to U.S. federal taxes										4,154
Tax credits										(389)	(289)	(552)
Enactment of the Tax Cuts and Jobs Act					$ 1,700					1,700	1,704
GILTI										662
Foreign rate differential										608	(164)	(46)
Other, net										47	80	39
Total tax	$ 4,301	$ 307	$ 363	$ 115		$ 2,250	$ 259	$ 216	$ 526	$ 5,086	$ 3,251	$ 1,102
Effective income tax rate										224.20%	80.10%	(3.30%)