Nature of operations and summary of significant accounting policies and going concern (Income Taxes) (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Accounting Policies [Abstract]
Effective income tax rate	0.00%	0.00%	0.00%	0.00%
Deferred tax benefit			$ 0
Uncertain tax positions	$ 0		0		$ 0
Net operating loss carryforwards subject to limitation	$ 760,067,000		$ 760,067,000