Share Based Payments - Summary of Stock Options Outstanding and Exercisable (Details)	12 Months Ended
	Dec. 31, 2018 $ / shares shares	Dec. 31, 2017 $ / shares shares	Dec. 31, 2016 $ / shares shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Options Outstanding \| shares	3,308,049	2,448,646	1,969,000
Exercise Price \| (per share)	$ 7.14	$ 7.35	$ 6.00
Number of Options Exercisable \| shares	1,918,672
Employee and Director Stock Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Options Outstanding \| shares	2,951,049
Grant Date Fair Value \| (per share)	$ 7.78	4.34
Number of Options Exercisable \| shares	1,599,172
Employee and Director Stock Options \| Option One
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Options Outstanding \| shares	360,000
Expiration Date	Jun. 18, 2019
Options Outstanding Remaining Contractual Life (In Years)	5 months 15 days
Exercise Price	$ 2.77
Fair Value Post Modification	$ 6.62
Number of Options Exercisable \| shares	360,000
Employee and Director Stock Options \| Option Two
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Options Outstanding \| shares	80,000
Expiration Date	Jun. 18, 2019
Options Outstanding Remaining Contractual Life (In Years)	5 months 15 days
Exercise Price	$ 2.77
Fair Value Post Modification	$ 6.62
Number of Options Exercisable \| shares	80,000
Employee and Director Stock Options \| Option Three
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Options Outstanding \| shares	20,000
Expiration Date	Dec. 08, 2019
Options Outstanding Remaining Contractual Life (In Years)	11 months 8 days
Exercise Price	$ 12.72
Fair Value Post Modification	$ 2.18
Number of Options Exercisable \| shares	20,000
Employee and Director Stock Options \| Option Four
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Options Outstanding \| shares	80,000
Expiration Date	Dec. 08, 2019
Options Outstanding Remaining Contractual Life (In Years)	11 months 8 days
Exercise Price	$ 12.72
Fair Value Post Modification	$ 2.18
Number of Options Exercisable \| shares	80,000
Employee and Director Stock Options \| Option Five
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Options Outstanding \| shares	20,000
Expiration Date	Mar. 16, 2020
Options Outstanding Remaining Contractual Life (In Years)	1 year 2 months 15 days
Exercise Price	$ 12.52
Fair Value Post Modification	$ 2.43
Number of Options Exercisable \| shares	20,000
Employee and Director Stock Options \| Option Six
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Options Outstanding \| shares	150,000
Expiration Date	Oct. 21, 2020
Options Outstanding Remaining Contractual Life (In Years)	1 year 9 months 21 days
Exercise Price	$ 3.20
Fair Value Post Modification	$ 6.57
Number of Options Exercisable \| shares	150,000
Employee and Director Stock Options \| Option Seven
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Options Outstanding \| shares	20,000
Expiration Date	Dec. 31, 2020
Options Outstanding Remaining Contractual Life (In Years)	2 years
Exercise Price	$ 4.48
Fair Value Post Modification	$ 5.86
Number of Options Exercisable \| shares	20,000
Employee and Director Stock Options \| Option Eight
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Options Outstanding \| shares	595,000
Expiration Date	Jul. 13, 2020
Options Outstanding Remaining Contractual Life (In Years)	1 year 6 months 10 days
Exercise Price	$ 5.35
Fair Value Post Modification	$ 5.18
Number of Options Exercisable \| shares	595,000
Employee and Director Stock Options \| Option Nine
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Options Outstanding \| shares	20,000
Expiration Date	Aug. 08, 2020
Options Outstanding Remaining Contractual Life (In Years)	1 year 7 months 6 days
Exercise Price	$ 4.98
Fair Value Post Modification	$ 5.42
Number of Options Exercisable \| shares	20,000
Employee and Director Stock Options \| Option Ten
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Options Outstanding \| shares	617,000
Expiration Date	Apr. 17, 2027
Options Outstanding Remaining Contractual Life (In Years)	8 years 3 months 14 days
Exercise Price	$ 8.13
Fair Value Post Modification	$ 7.54
Number of Options Exercisable \| shares	154,250
Employee and Director Stock Options \| Option Eleven
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Options Outstanding \| shares	6,146
Expiration Date	May 18, 2027
Options Outstanding Remaining Contractual Life (In Years)	8 years 4 months 13 days
Exercise Price	$ 7.35
Fair Value Post Modification	$ 4.75
Number of Options Exercisable \| shares	4,610
Employee and Director Stock Options \| Option Twelve
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Options Outstanding \| shares	10,000
Expiration Date	May 18, 2027
Options Outstanding Remaining Contractual Life (In Years)	8 years 4 months 13 days
Exercise Price	$ 7.35
Fair Value Post Modification	$ 7.65
Number of Options Exercisable \| shares	2,500
Employee and Director Stock Options \| Option Thirteen
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Options Outstanding \| shares	30,000
Expiration Date	Aug. 08, 2027
Options Outstanding Remaining Contractual Life (In Years)	8 years 7 months 6 days
Exercise Price	$ 10.38
Fair Value Post Modification	$ 7.38
Number of Options Exercisable \| shares	7,500
Employee and Director Stock Options \| Option Fourteen
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Options Outstanding \| shares	25,000
Expiration Date	Apr. 09, 2028
Options Outstanding Remaining Contractual Life (In Years)	9 years 3 months 7 days
Exercise Price	$ 9.03
Fair Value Post Modification	$ 8.01
Employee and Director Stock Options \| Option Fifteen
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Options Outstanding \| shares	337,500
Expiration Date	May 15, 2028
Options Outstanding Remaining Contractual Life (In Years)	9 years 4 months 13 days
Exercise Price	$ 10.99
Fair Value Post Modification	$ 7.89
Number of Options Exercisable \| shares	85,313
Employee and Director Stock Options \| Option Sixteen
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Options Outstanding \| shares	150,000
Expiration Date	Jul. 09, 2028
Options Outstanding Remaining Contractual Life (In Years)	9 years 6 months 7 days
Exercise Price	$ 9.69
Grant Date Fair Value	$ 6.83
Employee and Director Stock Options \| Options Seventeen
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Options Outstanding \| shares	75,726
Expiration Date	Aug. 22, 2028
Options Outstanding Remaining Contractual Life (In Years)	9 years 7 months 20 days
Exercise Price	$ 10.23
Grant Date Fair Value	$ 7.21
Employee and Director Stock Options \| Option Eighteen
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Options Outstanding \| shares	13,177
Expiration Date	Sep. 04, 2028
Options Outstanding Remaining Contractual Life (In Years)	9 years 8 months 1 day
Exercise Price	$ 10.19
Grant Date Fair Value	$ 7.19
Employee and Director Stock Options \| Option Nineteen
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Options Outstanding \| shares	50,000
Expiration Date	Sep. 10, 2028
Options Outstanding Remaining Contractual Life (In Years)	9 years 8 months 8 days
Exercise Price	$ 10.34
Grant Date Fair Value	$ 7.30
Employee and Director Stock Options \| Option Twenty
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Options Outstanding \| shares	50,000
Expiration Date	Sep. 24, 2028
Options Outstanding Remaining Contractual Life (In Years)	9 years 8 months 23 days
Exercise Price	$ 9.71
Grant Date Fair Value	$ 6.79
Employee and Director Stock Options \| Option Twenty One
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Options Outstanding \| shares	1,500
Expiration Date	Oct. 08, 2028
Options Outstanding Remaining Contractual Life (In Years)	9 years 9 months 3 days
Exercise Price	$ 8.25
Grant Date Fair Value	$ 5.84
Employee and Director Stock Options \| Option Twenty Two
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Options Outstanding \| shares	75,000
Expiration Date	Oct. 15, 2028
Options Outstanding Remaining Contractual Life (In Years)	9 years 9 months 10 days
Exercise Price	$ 8.75
Grant Date Fair Value	$ 6.19
Employee and Director Stock Options \| Option Twenty Three
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Options Outstanding \| shares	100,000
Expiration Date	Oct. 22, 2028
Options Outstanding Remaining Contractual Life (In Years)	9 years 9 months 18 days
Exercise Price	$ 10.16
Grant Date Fair Value	$ 7.20
Employee and Director Stock Options \| Option Twenty Four
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Options Outstanding \| shares	10,000
Expiration Date	Oct. 29, 2028
Options Outstanding Remaining Contractual Life (In Years)	9 years 9 months 25 days
Exercise Price	$ 9.71
Grant Date Fair Value	$ 6.87
Employee and Director Stock Options \| Option Twenty Five
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Options Outstanding \| shares	20,000
Expiration Date	Nov. 19, 2028
Options Outstanding Remaining Contractual Life (In Years)	9 years 10 months 17 days
Exercise Price	$ 8.00
Grant Date Fair Value	$ 5.66
Employee and Director Stock Options \| Option Twenty Six
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Options Outstanding \| shares	20,000
Expiration Date	Dec. 03, 2028
Options Outstanding Remaining Contractual Life (In Years)	9 years 11 months 1 day
Exercise Price	$ 8.66
Grant Date Fair Value	$ 6.13
Employee and Director Stock Options \| Option Twenty Seven
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Options Outstanding \| shares	15,000
Expiration Date	Dec. 17, 2028
Options Outstanding Remaining Contractual Life (In Years)	9 years 11 months 15 days
Exercise Price	$ 9.42
Grant Date Fair Value	$ 6.66
Consultants Stock Option
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Options Outstanding \| shares	357,000
Grant Date Fair Value \| (per share)	$ 8.87	$ 3.88
Number of Options Exercisable \| shares	319,500
Consultants Stock Option \| Option One
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Options Outstanding \| shares	80,000
Expiration Date	Jun. 18, 2019
Options Outstanding Remaining Contractual Life (In Years)	5 months 15 days
Exercise Price	$ 2.77
Fair Value Post Modification	$ 6.62
Number of Options Exercisable \| shares	80,000
Consultants Stock Option \| Option Two
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Options Outstanding \| shares	30,000
Expiration Date	Dec. 08, 2019
Options Outstanding Remaining Contractual Life (In Years)	11 months 8 days
Exercise Price	$ 12.72
Fair Value Post Modification	$ 2.18
Number of Options Exercisable \| shares	30,000
Consultants Stock Option \| Option Three
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Options Outstanding \| shares	72,000
Expiration Date	Oct. 03, 2020
Options Outstanding Remaining Contractual Life (In Years)	1 year 9 months 3 days
Exercise Price	$ 5.15
Fair Value Post Modification	$ 5.35
Number of Options Exercisable \| shares	72,000
Consultants Stock Option \| Option Four
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Options Outstanding \| shares	110,000
Expiration Date	Oct. 28, 2020
Options Outstanding Remaining Contractual Life (In Years)	1 year 9 months 25 days
Exercise Price	$ 3.18
Fair Value Post Modification	$ 6.59
Number of Options Exercisable \| shares	110,000
Consultants Stock Option \| Option Five
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Options Outstanding \| shares	20,000
Expiration Date	May 18, 2027
Options Outstanding Remaining Contractual Life (In Years)	8 years 4 months 13 days
Exercise Price	$ 7.35
Fair Value Post Modification	$ 7.65
Number of Options Exercisable \| shares	5,000
Consultants Stock Option \| Option Six
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Options Outstanding \| shares	15,000
Expiration Date	Aug. 08, 2027
Options Outstanding Remaining Contractual Life (In Years)	8 years 7 months 6 days
Exercise Price	$ 10.38
Fair Value Post Modification	$ 7.38
Number of Options Exercisable \| shares	3,750
Consultants Stock Option \| Option Seven
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Options Outstanding \| shares	15,000
Expiration Date	Nov. 06, 2027
Options Outstanding Remaining Contractual Life (In Years)	8 years 10 months 2 days
Exercise Price	$ 16.20
Fair Value Post Modification	$ 6.98
Number of Options Exercisable \| shares	3,750
Consultants Stock Option \| Option Eight
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Options Outstanding \| shares	15,000
Expiration Date	Aug. 22, 2028
Options Outstanding Remaining Contractual Life (In Years)	9 years 7 months 20 days
Exercise Price	$ 10.23
Grant Date Fair Value	$ 8.87
Number of Options Exercisable \| shares	15,000