Capital Stock (Details 3) - USD ($) | 12 Months Ended | | | |
Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015 | Dec. 31, 2014 |
Share-Based Compensation Arrangement By Share-Based Payment Award [Line Items] | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number | 3,780,244 | 4,096,818 | 5,022,186 | 6,263,112 |
Two Dollars Two Cents To Two Dollars Thirty Seven Cents [Member] | | | | |
Share-Based Compensation Arrangement By Share-Based Payment Award [Line Items] | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number | 415,024 | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term | 1 year 2 months 19 days | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price | $ 2.2 | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Intrinsic Value | $ 457,000 | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Number | 415,024 | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Remaining Contractual Term | 1 year 2 months 19 days | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Exercise Price | $ 2.2 | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Intrinsic Value | $ 457,000 | | | |
Two Dollars Thirty Eight Cents to Two Dollars Ninety Four Cents [Member] | | | | |
Share-Based Compensation Arrangement By Share-Based Payment Award [Line Items] | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number | 357,095 | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term | 4 years 9 months 10 days | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price | $ 2.58 | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Intrinsic Value | $ 257,000 | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Number | 315,845 | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Remaining Contractual Term | 4 years 3 months | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Exercise Price | $ 2.57 | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Intrinsic Value | $ 231,000 | | | |
Two Dollars Ninety Five Cents to Three Dollars Fifty Nine Cents [Member] | | | | |
Share-Based Compensation Arrangement By Share-Based Payment Award [Line Items] | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number | 321,239 | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term | 7 years 10 months 20 days | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price | $ 3.3 | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Intrinsic Value | $ 0 | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Number | 79,039 | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Remaining Contractual Term | 2 years 11 months 4 days | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Exercise Price | $ 3.35 | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Intrinsic Value | $ 0 | | | |
Three Dollars Sixty Cents To Three Dollars Ninety Five Cents [Member] | | | | |
Share-Based Compensation Arrangement By Share-Based Payment Award [Line Items] | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number | 277,429 | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term | 5 years 5 months 19 days | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price | $ 3.65 | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Intrinsic Value | $ 0 | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Number | 273,679 | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Remaining Contractual Term | 5 years 5 months 15 days | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Exercise Price | $ 3.65 | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Intrinsic Value | $ 0 | | | |
Three Dollars Ninety Six Cents to Four Dollars Eleven Cents [Member] | | | | |
Share-Based Compensation Arrangement By Share-Based Payment Award [Line Items] | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number | 252,282 | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term | 3 years 5 months 26 days | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price | $ 4.04 | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Intrinsic Value | $ 0 | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Number | 250,782 | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Remaining Contractual Term | 3 years 5 months 19 days | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Exercise Price | $ 4.04 | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Intrinsic Value | $ 0 | | | |
Four Dollars Twelve Cents To Four Dollars Seventeen Cents[Member] | | | | |
Share-Based Compensation Arrangement By Share-Based Payment Award [Line Items] | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number | 607,875 | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term | 6 years 4 months 28 days | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price | $ 4.12 | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Intrinsic Value | $ 0 | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Number | 452,750 | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Remaining Contractual Term | 6 years 4 months 28 days | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Exercise Price | $ 4.12 | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Intrinsic Value | $ 0 | | | |
Four Dollars Eighteen Cents To Four Dollars Twenty Six Cents [Member] | | | | |
Share-Based Compensation Arrangement By Share-Based Payment Award [Line Items] | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number | 71,500 | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term | 6 years 7 months 28 days | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price | $ 4.21 | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Intrinsic Value | $ 0 | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Number | 55,500 | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Remaining Contractual Term | 6 years 7 months 17 days | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Exercise Price | $ 4.21 | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Intrinsic Value | $ 0 | | | |
Four Dollars Twenty Seven Cents To Four Dollars Forty One Cents [Member] | | | | |
Share-Based Compensation Arrangement By Share-Based Payment Award [Line Items] | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number | 750,000 | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term | 5 years 10 months 17 days | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price | $ 4.31 | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Intrinsic Value | $ 0 | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Number | 750,000 | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Remaining Contractual Term | 5 years 10 months 17 days | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Exercise Price | $ 4.31 | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Intrinsic Value | $ 0 | | | |
Four Dollars Forty Two Cents To Five Dollars Fifty One Cents[Member] | | | | |
Share-Based Compensation Arrangement By Share-Based Payment Award [Line Items] | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number | 462,300 | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term | 7 years 1 month 20 days | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price | $ 5.37 | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Intrinsic Value | $ 0 | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Number | 273,175 | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Remaining Contractual Term | 7 years 1 month 9 days | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Exercise Price | $ 5.31 | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Intrinsic Value | $ 0 | | | |
Five Dollars Fifty Two Cents To Five Dollars Sixty Three Cents [Member] | | | | |
Share-Based Compensation Arrangement By Share-Based Payment Award [Line Items] | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number | 265,500 | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term | 7 years 4 months 28 days | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price | $ 5.56 | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Intrinsic Value | $ 0 | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Number | 132,750 | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Remaining Contractual Term | 7 years 4 months 28 days | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Exercise Price | $ 5.56 | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Intrinsic Value | $ 0 | | | |
Two Dollars Two Cents To Five Dollars Sixty Three Cents [Member] | | | | |
Share-Based Compensation Arrangement By Share-Based Payment Award [Line Items] | | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number | 3,780,244 | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term | 5 years 7 months 9 days | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price | $ 3.95 | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Intrinsic Value | $ 714,000 | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Number | 2,998,544 | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Remaining Contractual Term | 5 years 7 days | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Exercise Price | $ 3.84 | | | |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Intrinsic Value | $ 688,000 | | | |