Revenue Recognition - Schedule of License, Royal and Other Revenue (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Royalty Revenue [Member] | Sublicense Agreement [Member] | CamelBak [Member]
Revenue	[1]				$ 100
Royalty Revenue [Member] | License Agreement [Member] | Bellco [Member]
Revenue		10	21	50	79
Other Revenue [Member]
Revenue		31	55	56	74
Royalty and Other Revenue [Member]
Revenue		$ 41	$ 76	$ 106	$ 253

[1] In May 2015, the Company entered into a Sublicense Agreement with CamelBak Products, LLC ("CamelBak"). Under the Sublicense Agreement, the Company granted CamelBak an exclusive, non-transferable, worldwide (with the exception of Italy) sublicense and license, in each case solely to market, sell, distribute, import and export the Company's individual water treatment device. In exchange for the rights granted to CamelBak, CamelBak agreed, through December 31, 2022, to pay the Company a percentage of the gross profit on any sales made to a branch of the U.S. military, subject to certain exceptions, and to pay a fixed per-unit fee for any other sales made. CamelBak was also required to meet or exceed certain minimum annual fees payable to the Company, and if such fees are not met or exceeded, the Company may convert the exclusive sublicense to a non-exclusive sublicense with respect to non-U.S. military sales. In the first quarter of 2019, the Sublicense Agreement was amended to eliminate the minimum fee obligations starting May 6, 2018 and, as such, Camelbak has no further minimum fee obligations.