Stockholders' equity (Narrative) (Details) (USD $)	3 Months Ended	9 Months Ended	3 Months Ended	9 Months Ended	3 Months Ended	9 Months Ended		3 Months Ended	9 Months Ended	3 Months Ended	9 Months Ended		3 Months Ended	9 Months Ended																			3 Months Ended	9 Months Ended	3 Months Ended	9 Months Ended
	Sep. 30, 2014	Sep. 30, 2014	Sep. 30, 2014 President [Member]	Sep. 30, 2014 President [Member]	Sep. 30, 2014 Twenty Four Employees [Member]	Sep. 30, 2014 Twenty Four Employees [Member]	Sep. 30, 2014 Director [Member]	Sep. 30, 2014 Chief Executive Officer [Member]	Sep. 30, 2014 Chief Executive Officer [Member]	Sep. 30, 2014 EmployeeStockOptionMember	Sep. 30, 2014 EmployeeStockOptionMember	Sep. 30, 2014 EmployeeStockOptionMember President [Member]	Sep. 30, 2014 EmployeeStockOptionMember Director [Member]	Sep. 30, 2014 EmployeeStockOptionMember Director [Member]	Sep. 30, 2014 EmployeeStockOptionMember Vice Chairman Board of Directors [Member]	Sep. 30, 2014 EmployeeStockOptionMember Board Member One [Member]	Sep. 30, 2014 EmployeeStockOptionMember Board Member Two [Member]	Sep. 30, 2014 EmployeeStockOptionMember Board Member Three [Member]	Sep. 30, 2014 EmployeeStockOptionMember Board Member Four [Member]	Sep. 30, 2014 EmployeeStockOptionMember Board Member August Increase [Member]	Sep. 30, 2014 EmployeeStockOptionMember Board Member Five [Member]	Sep. 30, 2014 EmployeeStockOptionMember Board Member Six [Member]	Sep. 30, 2014 EmployeeStockOptionMember Board Member Seven [Member]	Sep. 30, 2014 EmployeeStockOptionMember Board Member Eight [Member]	Sep. 30, 2014 EmployeeStockOptionMember Board Member Nine [Member]	Sep. 30, 2014 EmployeeStockOptionMember Board Member Ten [Member]	Sep. 30, 2014 First Equity Incentive Plan [Member]	Sep. 30, 2014 Second Equity Incentive Plan [Member]	Jun. 16, 2014 Third Equity Incentive Plan [Member]	Jun. 15, 2014 Third Equity Incentive Plan [Member]	Apr. 21, 2014 Third Equity Incentive Plan [Member]	Apr. 20, 2014 Third Equity Incentive Plan [Member]	Sep. 30, 2014 Warrants [Member]	Sep. 30, 2014 Warrants [Member]	Sep. 30, 2014 Warrants [Member] Investors [Member]	Sep. 30, 2014 Warrants [Member] Investors [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum shares authorized for issuance																															10,000,000	3,000,000			22,835,591	22,835,591
Maximum shares authorized for issuance by the entity's stockholders																													10,000,000	3,000,000
Shares available under the award		45,000					45,000													900,000
Outstanding	33,077,886	33,077,886								7,374,667	7,374,667																266,667	1,666,667					3,717,324	3,717,324	21,985,895	21,985,895
Vested										4,214,630	4,214,630																						3,498,807	3,498,807
Term				5 years		5 years	5 years		5 years		5 years			5 years
Grants in period				400,000		1,410,000	405,000		350,000	163,000	5,918,000	300,000		1,850,000	500,000	100,000	500,000	250,000	200,000		200,000	225,000	175,000	175,000	100,000	25,000									0	16,289,704
Exercise price per share				$ 1.15		$ 1.15	$ 0.87		$ 1.15					$ 0.87						$ 1.14
Expirations																																		97,333
Cancelled																																		66,667
Fair value				$ 221,629		$ 781,243			$ 193,925					$ 1,068,350						$ 73,214,600
Stock-based compensation expense	141,260,100	450,554,600	15,096	82,861	5,449,900	34,595,300	247,939	1,392,300	8,642,600				13,943,600	58,329,300						73,214,600
Weighted average exercise price per share																																	$ 2.49	$ 2.49
Weighted average remaining contractual term																																	42 months 18 days
Unrecognized compensation expense	$ 230,087,400	$ 230,087,400																															$ 229,887,400	$ 229,887,400