Stockholders' Equity (Warrants and Options) (Narrative) (Details) - USD ($)			12 Months Ended
	May 02, 2016	Oct. 21, 2015	Dec. 31, 2018		Dec. 31, 2017	Dec. 31, 2016	Jan. 13, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Outstanding options and warrants, Intrinsic value			$ 692,000		$ 2,438,000	$ 2,400,000
Unrecognized compensation cost related to non vested stock			$ 51,000
Warrants issued			1,597,697		4,360,907	1,088,916
Common stock issued			66,405,180		55,888,399
Principal amount			$ 3,266,700		$ 3,358,900
Rights Offering Senior Convertible Bonds Rights Offering [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Subscriptions shares		360,000
Debt conversion, description			Under the rights offering, the Company distributed at no cost, 360,000 non-transferable subscription rights to subscribe for, on a per right basis, two 10% Convertible Senior Bonds par $100 due May 2, 2021 (the "Notes due May 2021"), to persons who owned shares of the Company's Common Stock on October 15, 2015, the record date for the offering. Each whole subscription right entitled the participant to purchase two convertible bonds at a purchase price of $100 per bond.
Convertible senior bonds par value		$ 100
Convertible bonds purchase price		$ 100
Description of maturity date			The offering was scheduled to terminate on January 15, 2016 but was extended to March 31, 2016. On March 31, 2016, the rights offering terminated.
Debt instrument, maturity date		May 02, 2021
Principal amount	$ 3,470,000
Net proceeds from sale of the Notes	3,334,000
Convertible senior bonds percentage		10.00%
Expenses from rights offering	$ 136,000
Warrants and Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options reserved for exercisable to employees and non-employees			10,835,333
Stock options exercisable, shares			10,825,333
Outstanding options and warrants, Intrinsic value			$ 561,000
Outstanding options and warrants, shares			10,835,333
Dividend Reinvestment and Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unit option, description			On November 1, 2016, the Company launched a unit offering (the "Unit Program") under the Company's DSPP pursuant to which participants could purchase units comprised of seven shares of Common Stock and seven Common Stock purchase warrants, at a per unit purchase price of $10.
Unit program terminate			Mar. 31, 2017
Warrants termination, description			The warrants became first exercisable on May 2, 2016 and, in the case of ZNWAB continued to be exercisable through May 2, 2017 (1 year), May 2, 2018 for ZNWAC (2 years) and May 2, 2019 for ZNWAD (3 years), respectively, at a per share exercise price of $1.00.
Expenses from rights offering			$ 243,000
Proceeds from the sale of the rights			$ 3,038,000
Subscription rights offering, description			On April 2, 2018 the Company announced an offering ("2018 Subscription Rights Offering") through American Stock Transfer & Trust Company, LLC (the "Subscription Agent"), at no cost to the shareholders, of non-transferable Subscription Rights to purchase Rights (each "Right" and collectively, the "Rights") of its securities to persons who owned shares of our Common Stock on April 13, 2018 ("the Record Date"). Pursuant to the 2018 Subscription Rights Offering, each holder of shares of common stock on the Record Date received non-transferable rights to subscribe for Rights, with each Right comprised of one share of the Company Common Stock, par value $0.01 per share (the "Common Stock") and one Common Stock Purchase Warrant to purchase an additional one share of Common Stock. Each Right may be purchased at a per Right subscription price of $5.00. Each Warrant affords the investor the opportunity to purchase one share of the Company Common Stock at a warrant exercise price of $3.00. The warrant is referred to as "ZNWAI."
Warrant [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Amount of funds raised under the DSPP program			$ 13,781,000		$ 22,994,000	$ 4,338,000
Warrant [Member] | New Unit Program [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Purchase warrants unit price			$ 1.00				$ 4.00
Exercise price per unit							$ 1.00
New unit program began date			Mar. 22, 2017
New unit program termination date			Jul. 12, 2017
New unit program, description			This New Unit Program enabled participants to purchase Units of the Company's securities where each Unit (priced at $250.00 each) was comprised of (i) the number of shares of Common Stock determined by dividing $250.00 (the price of one Unit) by the average of the high and low sale prices of the Company's Common Stock as reported on the NASDAQ on the unit purchase date and (ii) Common Stock purchase warrants to purchase an additional 25 shares of Common Stock at a warrant exercise price of $1.00 per share. The warrant is referred to as "ZNWAF."
Warrant [Member] | Dividend Reinvestment and Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Warrants termination, description			The ZNWAE warrants became exercisable on May 1, 2017, which is the 31st day following the Unit Option Termination Date (i.e., on March 31, 2017) and continue to be exercisable through May 1, 2020 (3 years) at a per share exercise price of $1.00. If the Company's Common Stock trades above $5.00 per share at the closing price for 15 consecutive trading days at any time prior to the expiration date of the warrant, the Company has the sole discretion to terminate the warrant early upon providing 60 days advanced notice to warrant holders.
ZNWAF Warrants [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Purchase warrants unit price			$ 1.00	[1],[2]		$ 1.00
Warrants issued			100		683,865
ZNWAF Warrants [Member] | Unit Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Warrants termination, description			The warrants became exercisable on October 29, 2018 and continue to be exercisable through October 29, 2020 at a per share exercise price of $1.00, after the Company, on December 4, 2018, extended the termination date of the Warrant by one (1) year from the expiration date of April 19, 2019 to April 19, 2020.
New unit program, description			On August 21, 2018, the Company initiated another Unit Option and it and terminated on September 26, 2018. The Unit Option consisted of Units of the Company's securities where each Unit (priced at $250.00 each) was comprised of (i) a certain number of shares of Common Stock determined by dividing $250.00 (the price of one Unit) by the average of the high and low sale prices of the Company's publicly traded common stock as reported on the NASDAQ on the Unit Purchase Date and (ii) Common Stock purchase warrants to purchase an additional twenty-five (25) shares of Common Stock. The investor's Plan account was credited with the number of shares of the Company's Common Stock acquired under the Units purchased. Each warrant affords the investor the opportunity to purchase one share of Company Common Stock at a warrant exercise price of $1.00. The warrant is referred to as "ZNWAJ."
ZNWAF Warrants [Member] | Unit Option Began [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Warrants termination, description			The warrants became exercisable on February 25, 2019 and continue to be exercisable through February 25, 2020 at a per share exercise price of $0.01.
New unit program, description			The Unit Option consisted of Units of the Company's securities where each Unit (priced at $250.00 each) is comprised of (i) two hundred and fifty (250) shares of Common Stock and (ii) Common Stock purchase warrants to purchase an additional two hundred and fifty (250) shares of Common Stock at a per share exercise price of $0.01. The investor's Plan account will be credited with the number of shares of the Company's Common Stock and Warrants that are acquired under the Units purchased. Each warrant affords the participant the opportunity to purchase one share of our Common Stock at a warrant exercise price of $0.01. The warrant is referred to as "ZNWAK."
ZNWAF Warrants [Member] | Warrant [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise price per unit			$ 1.00
Warrants termination, description			All ZNWAF warrants became exercisable on August 14, 2017 and continue to be exercisable through August 14, 2020 at a per share exercise price of $1.00. The warrant terms provide that if the Company's Common Stock trades above $5.00 per share as the closing price for 15 consecutive trading days at any time prior to the expiration date of the warrant, the Company has the sole discretion to accelerate the termination date of the warrant upon providing 60 days advanced notice to the warrant holders.
ZNWAG Warrants [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Purchase warrants unit price			$ 1.00	[2]		$ 1.00
Warrants issued			6,030		414,300
ZNWAG Warrants [Member] | Unit Option Program [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Warrants termination, description			The warrants became exercisable on January 8, 2018 and continue to be exercisable through January 8, 2021 at a per share exercise price of $1.00. The warrant terms provide that if the Company's Common Stock trades above $5.00 per share as the closing price for 15 consecutive trading days at any time prior to the expiration date of the warrant, the Company has the sole discretion to accelerate the termination date of the warrant upon providing 60 days advanced notice to the warrant holders.
New unit program began date			Feb. 01, 2018
New unit program termination date			Feb. 28, 2018
New unit program, description			The Unit Option consisted of Units of our securities where each Unit (priced at $250.00 each) was comprised of (i) 50 shares of Common Stock and (ii) Common Stock purchase warrants to purchase an additional 50 shares of Common Stock. The investor's Plan account was credited with the number of shares of the Company's Common Stock acquired under the Units purchased. Each warrant affords the investor the opportunity to purchase one share of Company Common Stock at a warrant exercise price of $5.00. The warrant is referred to as "ZNWAH."
ZNWAH Warrants [Member
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Purchase warrants unit price			$ 5.00	[1],[2]		$ 5.00
Warrants issued			373,900
ZNWAH Warrants [Member | Unit Option Program [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Warrants termination, description			The warrants became exercisable on April 2, 2018 and continue to be exercisable through April 2, 2020 at a per share exercise price of $5.00, after the Company, on December 4, 2018, extended the termination date of the Warrant by one (1) year from the expiration date of April 19, 2019 to April 19, 2020.
2018 Subscription Rights Offering [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expenses from rights offering			$ 243,000
Proceeds from the sale of the rights			$ 3,038,000
Subscription rights offering, description			On April 2, 2018 the Company announced an offering ("2018 Subscription Rights Offering") through American Stock Transfer & Trust Company, LLC (the "Subscription Agent"), at no cost to the shareholders, of non-transferable Subscription Rights to purchase Rights (each "Right" and collectively, the "Rights") of its securities to persons who owned shares of our Common Stock on April 13, 2018 ("the Record Date"). Pursuant to the 2018 Subscription Rights Offering, each holder of shares of common stock on the Record Date received non-transferable rights to subscribe for Rights, with each Right comprised of one share of the Company Common Stock, par value $0.01 per share (the "Common Stock") and one Common Stock Purchase Warrant to purchase an additional one share of Common Stock. Each Right could be purchased at a per Right subscription price of $5.00. Each Warrant afforded the investor the opportunity to purchase one share of the Company Common Stock at a warrant exercise price of $3.00. The warrant is referred to as "ZNWAI."

[1] On December 4, 2018, the Company extended the termination date of the Warrants by one (1) year.

[2] Zion's ZNWAB Warrants expired on May 2, 2017 and its ZNWAC Warrants expired on May 2, 2018