Summary of Significant Accounting Policies (Narrative) (Details) - USD ($) $ in Thousands		3 Months Ended
	Mar. 24, 2017	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016	Dec. 21, 2016	Dec. 31, 2015
Accounting Policies [Line Items]
Accumulated deficit		$ (220,986)		$ (218,987)
Net loss		(1,999)	$ 14
Net cash used in operating and investing activities		1,200
Cash and cash equivalents		3,750	9,050	$ 5,241		$ 9,273
Total intangible amortization expense		$ 14	$ 14
Standard product warranty period		1 year
Revolving Credit Facility [Member]
Accounting Policies [Line Items]
Outstanding borrowings, gross		$ 1,700
Remaining borrowing capacity		$ 2,300
Maximum borrowing capacity					$ 5,000
Unsecured Financing Arrangement With Largest Investor [Member]
Accounting Policies [Line Items]
Expiration date	Jun. 30, 2020
Working Capital Purposes [Member] | Unsecured Financing Arrangement With Largest Investor [Member]
Accounting Policies [Line Items]
Expiration date	Jun. 30, 2018
Maximum borrowing capacity	$ 2,000
Availability Should Current Lender Not Provide Under Normal Terms and Conditions [Member] | Unsecured Financing Arrangement With Largest Investor [Member]
Accounting Policies [Line Items]
Maximum borrowing capacity	$ 3,000