Segment Reporting (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2013
Segment Reporting Information [Line Items]
Sales	$ 3,167	$ 7,668
Gross profit	2,170	5,477
Total assets	16,002		17,221
Reporting Segments
Segment Reporting Information [Line Items]
Sales	3,167	7,668
Gross profit	2,170	5,477
Total assets	16,002	24,791
Reporting Segments | ZMI & ZBC
Segment Reporting Information [Line Items]
Sales	3,105	7,606
Gross profit	2,144	5,430
Total assets	15,291	24,142
Reporting Segments | ZND & ZEU
Segment Reporting Information [Line Items]
Sales	62	62
Gross profit	26	47
Total assets	704	625
Reporting Segments | ZMS
Segment Reporting Information [Line Items]
Total assets	$ 7	$ 24