Stockholders' Equity (Stock Options Outstanding) (Details)	12 Months Ended
	Dec. 31, 2018 $ / shares shares
Vested [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Shares underlying outstanding options Range of exercise price, lower range	$ 0.01
Shares underlying outstanding options Range of exercise price, upper range	$ 4.15
Shares underlying outstanding options Number Outstanding | shares	4,778,443
Shares underlying outstanding options Weighted Average Exercise price	$ 1.38
Vested [Member] | Range of exercise price 0.01 One [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Shares underlying outstanding options Range of exercise price	$ 0.01
Shares underlying outstanding options Number Outstanding | shares	15,000
Shares underlying outstanding options Weighted average remaining contractual life (years)	4 years 10 months 14 days
Shares underlying outstanding options Weighted Average Exercise price	$ 0.01
Vested [Member] | Range of exercise price 0.01 Two [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Shares underlying outstanding options Range of exercise price	$ 0.01
Shares underlying outstanding options Number Outstanding | shares	15,000
Shares underlying outstanding options Weighted average remaining contractual life (years)	5 years 2 months 30 days
Shares underlying outstanding options Weighted Average Exercise price	$ 0.01
Vested [Member] | Range of exercise price 0.01 Three [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Shares underlying outstanding options Range of exercise price	$ 0.01
Shares underlying outstanding options Number Outstanding | shares	5,000
Shares underlying outstanding options Weighted average remaining contractual life (years)	5 years 5 months 12 days
Shares underlying outstanding options Weighted Average Exercise price	$ 0.01
Vested [Member] | Range of exercise price 0.01 Four [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Shares underlying outstanding options Range of exercise price	$ 0.01
Shares underlying outstanding options Number Outstanding | shares	10,000
Shares underlying outstanding options Weighted average remaining contractual life (years)	6 years 9 months
Shares underlying outstanding options Weighted Average Exercise price	$ 0.01
Vested [Member] | Range of exercise price 0.01 Five [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Shares underlying outstanding options Range of exercise price	$ 0.01
Shares underlying outstanding options Number Outstanding | shares	25,000
Shares underlying outstanding options Weighted average remaining contractual life (years)	7 years
Shares underlying outstanding options Weighted Average Exercise price	$ 0.01
Vested [Member] | Range of exercise price 0.01 Six [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Shares underlying outstanding options Range of exercise price	$ 0.01
Shares underlying outstanding options Number Outstanding | shares	305,000
Shares underlying outstanding options Weighted average remaining contractual life (years)	7 years 5 months 1 day
Shares underlying outstanding options Weighted Average Exercise price	$ 0.01
Vested [Member] | Range Exercise Price 0.01 Seven [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Shares underlying outstanding options Range of exercise price	$ 0.01
Shares underlying outstanding options Number Outstanding | shares	525,000
Shares underlying outstanding options Weighted average remaining contractual life (years)	8 years
Shares underlying outstanding options Weighted Average Exercise price	$ 0.01
Vested [Member] | Range Exercise Price 0.01 Eight [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Shares underlying outstanding options Range of exercise price	$ 0.01
Shares underlying outstanding options Number Outstanding | shares	10,000
Shares underlying outstanding options Weighted average remaining contractual life (years)	8 years 4 days
Shares underlying outstanding options Weighted Average Exercise price	$ 0.01
Vested [Member] | Range Exercise Price 0.01 Nine [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Shares underlying outstanding options Range of exercise price	$ 0.01
Shares underlying outstanding options Number Outstanding | shares	60,000
Shares underlying outstanding options Weighted average remaining contractual life (years)	8 years 3 months 15 days
Shares underlying outstanding options Weighted Average Exercise price	$ 0.01
Vested [Member] | Range Exercise Price 0.01 Ten [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Shares underlying outstanding options Range of exercise price	$ 0.01
Shares underlying outstanding options Number Outstanding | shares	30,000
Shares underlying outstanding options Weighted average remaining contractual life (years)	8 years 9 months
Shares underlying outstanding options Weighted Average Exercise price	$ 0.01
Vested [Member] | Range Exercise Price 0.01 Eleven [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Shares underlying outstanding options Range of exercise price	$ 0.01
Shares underlying outstanding options Number Outstanding | shares	232,500
Shares underlying outstanding options Weighted average remaining contractual life (years)	9 years
Shares underlying outstanding options Weighted Average Exercise price	$ 0.01
Vested [Member] | Range Exercise Price 0.01 Twelve [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Shares underlying outstanding options Range of exercise price	$ 0.01
Shares underlying outstanding options Number Outstanding | shares	110,000
Shares underlying outstanding options Weighted average remaining contractual life (years)	9 years 4 days
Shares underlying outstanding options Weighted Average Exercise price	$ 0.01
Vested [Member] | Range Exercise Price 0.01 Thirteen [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Shares underlying outstanding options Range of exercise price	$ 0.01
Shares underlying outstanding options Number Outstanding | shares	45,000
Shares underlying outstanding options Weighted average remaining contractual life (years)	9 years 1 month 27 days
Shares underlying outstanding options Weighted Average Exercise price	$ 0.01
Vested [Member] | Range of exercise price 0.01 Fourteen [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Shares underlying outstanding options Range of exercise price	$ 0.01
Shares underlying outstanding options Number Outstanding | shares	6,000
Shares underlying outstanding options Weighted average remaining contractual life (years)	9 years 3 months 4 days
Shares underlying outstanding options Weighted Average Exercise price	$ 0.01
Vested [Member] | Range of exercise price 1.33 Fifteen [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Shares underlying outstanding options Range of exercise price	$ 1.33
Shares underlying outstanding options Number Outstanding | shares	25,000
Shares underlying outstanding options Weighted average remaining contractual life (years)	4 years 3 months 26 days
Shares underlying outstanding options Weighted Average Exercise price	$ 1.38
Vested [Member] | Range of exercise price 1.38 Sixteen [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Shares underlying outstanding options Range of exercise price	$ 1.38
Shares underlying outstanding options Number Outstanding | shares	108,000
Shares underlying outstanding options Weighted average remaining contractual life (years)	2 years 4 days
Shares underlying outstanding options Weighted Average Exercise price	$ 1.38
Vested [Member] | Range of exercise price 1.38 Seventeen [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Shares underlying outstanding options Range of exercise price	$ 1.38
Shares underlying outstanding options Number Outstanding | shares	123,057
Shares underlying outstanding options Weighted average remaining contractual life (years)	6 years 4 days
Shares underlying outstanding options Weighted Average Exercise price	$ 1.38
Vested [Member] | Range of exercise price 1.55 Eighteen [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Shares underlying outstanding options Range of exercise price	$ 1.55
Shares underlying outstanding options Number Outstanding | shares	400,000
Shares underlying outstanding options Weighted average remaining contractual life (years)	3 years 5 months 5 days
Shares underlying outstanding options Weighted Average Exercise price	$ 1.38
Vested [Member] | Range of exercise price 1.67 Nineteen [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Shares underlying outstanding options Range of exercise price	$ 1.67
Shares underlying outstanding options Number Outstanding | shares	340,000
Shares underlying outstanding options Weighted average remaining contractual life (years)	1 year 9 months
Shares underlying outstanding options Weighted Average Exercise price	$ 1.67
Vested [Member] | Range of exercise price 1.67 Twenty [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Shares underlying outstanding options Range of exercise price	$ 1.67
Shares underlying outstanding options Number Outstanding | shares	448,886
Shares underlying outstanding options Weighted average remaining contractual life (years)	5 years 9 months 3 days
Shares underlying outstanding options Weighted Average Exercise price	$ 1.67
Vested [Member] | Range of exercise price 1.70 Twenty One [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Shares underlying outstanding options Range of exercise price	$ 1.70
Shares underlying outstanding options Number Outstanding | shares	298,500
Shares underlying outstanding options Weighted average remaining contractual life (years)	3 years 11 months 19 days
Shares underlying outstanding options Weighted Average Exercise price	$ 1.70
Vested [Member] | Range of exercise price 1.73 Twenty Two [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Shares underlying outstanding options Range of exercise price	$ 1.73
Shares underlying outstanding options Number Outstanding | shares	25,000
Shares underlying outstanding options Weighted average remaining contractual life (years)	7 days
Shares underlying outstanding options Weighted Average Exercise price	$ 1.73
Vested [Member] | Range of exercise price 1.75 Twenty Three [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Shares underlying outstanding options Range of exercise price	$ 1.75
Shares underlying outstanding options Number Outstanding | shares	400,000
Shares underlying outstanding options Weighted average remaining contractual life (years)	4 years 6 months 7 days
Shares underlying outstanding options Weighted Average Exercise price	$ 1.700
Vested [Member] | Range of exercise price 1.87 Twenty Four [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Shares underlying outstanding options Range of exercise price	$ 1.87
Shares underlying outstanding options Number Outstanding | shares	25,000
Shares underlying outstanding options Weighted average remaining contractual life (years)	3 years 1 month 2 days
Shares underlying outstanding options Weighted Average Exercise price	$ 1.87
Vested [Member] | Range of exercise price 1.95 Twenty Five [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Shares underlying outstanding options Range of exercise price	$ 1.95
Shares underlying outstanding options Number Outstanding | shares	25,000
Shares underlying outstanding options Weighted average remaining contractual life (years)	1 year 2 months 30 days
Shares underlying outstanding options Weighted Average Exercise price	$ 1.95
Vested [Member] | Range of exercise price 1.96 Twenty Six [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Shares underlying outstanding options Range of exercise price	$ 1.96
Shares underlying outstanding options Number Outstanding | shares	25,000
Shares underlying outstanding options Weighted average remaining contractual life (years)	8 months 2 days
Shares underlying outstanding options Weighted Average Exercise price	$ 1.96
Vested [Member] | Range of exercise price 2.03 Twenty Seven [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Shares underlying outstanding options Range of exercise price	$ 2.03
Shares underlying outstanding options Number Outstanding | shares	25,000
Shares underlying outstanding options Weighted average remaining contractual life (years)	2 years 3 months 29 days
Shares underlying outstanding options Weighted Average Exercise price	$ 2.03
Vested [Member] | Range of exercise price 2.31 Twenty Eight [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Shares underlying outstanding options Range of exercise price	$ 2.31
Shares underlying outstanding options Number Outstanding | shares	400,000
Shares underlying outstanding options Weighted average remaining contractual life (years)	5 years 4 days
Shares underlying outstanding options Weighted Average Exercise price	$ 2.31
Vested [Member] | Range of exercise price 2.61 Twenty Nine [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Shares underlying outstanding options Range of exercise price	$ 2.61
Shares underlying outstanding options Number Outstanding | shares	681,500
Shares underlying outstanding options Weighted average remaining contractual life (years)	2 years 11 months 4 days
Shares underlying outstanding options Weighted Average Exercise price	$ 2.61
Vested [Member] | Range of exercise price 4.15 Thirty [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Shares underlying outstanding options Range of exercise price	$ 4.15
Shares underlying outstanding options Number Outstanding | shares	25,000
Shares underlying outstanding options Weighted average remaining contractual life (years)	5 years 6 months 3 days
Shares underlying outstanding options Weighted Average Exercise price	$ 4.15
Non-vested [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Shares underlying outstanding options Range of exercise price	$ 0.01
Shares underlying outstanding options Number Outstanding | shares	10,000
Shares underlying outstanding options Weighted Average Exercise price	$ 0.01
Non-vested [Member] | Range Exercise Price 0.01 Ten [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Shares underlying outstanding options Range of exercise price	$ 0.01
Shares underlying outstanding options Number Outstanding | shares	10,000
Shares underlying outstanding options Weighted average remaining contractual life (years)	8 years 9 months
Shares underlying outstanding options Weighted Average Exercise price	$ 0.01