GUARANTEES (Details)	12 Months Ended
Dec. 31, 2015
GUARANTEES [Abstract]
Standard product warranty period	1 year

Warranty period of standard product, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

No definition available.

Name:	ztho_StandardProductWarrantyPeriod
Namespace Prefix:	ztho_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration