Schedule of Long-term restricted cash and bond reserves (Details)	6 Months Ended
	Jun. 30, 2016 USD ($)
Restricted Cash And Security Bond Reserves Schedule Of Long-term Restricted Cash And Bond Reserves 1	$ 1,468,898
Restricted Cash And Security Bond Reserves Schedule Of Long-term Restricted Cash And Bond Reserves 2	1,468,898
Restricted Cash And Security Bond Reserves Schedule Of Long-term Restricted Cash And Bond Reserves 3	1,035,627
Restricted Cash And Security Bond Reserves Schedule Of Long-term Restricted Cash And Bond Reserves 4	708,300
Restricted Cash And Security Bond Reserves Schedule Of Long-term Restricted Cash And Bond Reserves 5	632,895
Restricted Cash And Security Bond Reserves Schedule Of Long-term Restricted Cash And Bond Reserves 6	314,590
Restricted Cash And Security Bond Reserves Schedule Of Long-term Restricted Cash And Bond Reserves 7	1,807,890
Restricted Cash And Security Bond Reserves Schedule Of Long-term Restricted Cash And Bond Reserves 8	0
Restricted Cash And Security Bond Reserves Schedule Of Long-term Restricted Cash And Bond Reserves 9	2,943,141
Restricted Cash And Security Bond Reserves Schedule Of Long-term Restricted Cash And Bond Reserves 10	0
Restricted Cash And Security Bond Reserves Schedule Of Long-term Restricted Cash And Bond Reserves 11	270,000
Restricted Cash And Security Bond Reserves Schedule Of Long-term Restricted Cash And Bond Reserves 12	270,000
Restricted Cash And Security Bond Reserves Schedule Of Long-term Restricted Cash And Bond Reserves 13	2,466,270
Restricted Cash And Security Bond Reserves Schedule Of Long-term Restricted Cash And Bond Reserves 14	2,542,058
Restricted Cash And Security Bond Reserves Schedule Of Long-term Restricted Cash And Bond Reserves 15	4,507,969
Restricted Cash And Security Bond Reserves Schedule Of Long-term Restricted Cash And Bond Reserves 16	4,507,110
Restricted Cash And Security Bond Reserves Schedule Of Long-term Restricted Cash And Bond Reserves 17	5,070,001
Restricted Cash And Security Bond Reserves Schedule Of Long-term Restricted Cash And Bond Reserves 18	4,966,543
Restricted Cash And Security Bond Reserves Schedule Of Long-term Restricted Cash And Bond Reserves 19	2,471,689
Restricted Cash And Security Bond Reserves Schedule Of Long-term Restricted Cash And Bond Reserves 20	2,718,290
Restricted Cash And Security Bond Reserves Schedule Of Long-term Restricted Cash And Bond Reserves 21	22,674,380
Restricted Cash And Security Bond Reserves Schedule Of Long-term Restricted Cash And Bond Reserves 22	$ 17,495,789