Stockholders' equity (Details 1)	Sep. 30, 2015 $ / shares shares
Outstanding	34,423,201
4th Qtr, 2015 [Member]
Outstanding	478,312
Weighted Average Exercise Price | $ / shares	$ 7.53
1st Qtr, 2016 [Member]
Outstanding	300,000
Weighted Average Exercise Price | $ / shares	$ 6.50
2nd Qtr, 2016 [Member]
Outstanding	1,465,833
Weighted Average Exercise Price | $ / shares	$ 6.75
3rd Qtr, 2016 [Member]
Outstanding	625
Weighted Average Exercise Price | $ / shares	$ 9.00
4th Qtr, 2016 [Member]
Outstanding	666,811
Weighted Average Exercise Price | $ / shares	$ 7.55
1st Qtr, 2017 [Member]
Outstanding	34,749
Weighted Average Exercise Price | $ / shares	$ 7.99
2nd Qtr, 2017 [Member]
Outstanding	1,709,810
Weighted Average Exercise Price | $ / shares	$ 7.05
3rd Qtr, 2017 [Member]
Outstanding	576,430
Weighted Average Exercise Price | $ / shares	$ 1.53
4th Qtr, 2017 [Member]
Outstanding	1,542,338
Weighted Average Exercise Price | $ / shares	$ 6.71
4th Qtr, 2018 [Member]
Outstanding	10,000
Weighted Average Exercise Price | $ / shares	$ 6.60
1st Qtr, 2019 [Member]
Outstanding	22,275,623
Weighted Average Exercise Price | $ / shares	$ 1.09
2nd Qtr, 2019 [Member]
Outstanding	893,336
Weighted Average Exercise Price | $ / shares	$ 0.92
3rd Qtr. 2019 [Member]
Outstanding	1,113,000
Weighted Average Exercise Price | $ / shares	$ 1.16
4th Qtr, 2019 [Member]
Outstanding	2,623,000
Weighted Average Exercise Price | $ / shares	$ 1.15
1st Qtr, 2020 [Member]
Outstanding	525,000
Weighted Average Exercise Price | $ / shares	$ 0.92
2nd Qtr, 2020 [Member]
Outstanding	75,000
Weighted Average Exercise Price | $ / shares	$ 0.65
4th Qtr, 2022 [Member]
Outstanding	133,334
Weighted Average Exercise Price | $ / shares	$ 7.05