Summary of Significant Accounting Policies - Property and Equipment (Details) - USD ($)	Dec. 31, 2016	Dec. 31, 2015
Significant Accounting Policies [Line Items]
Property and equipment, Gross	$ 6,608,735	$ 6,658,727
Less accumulated depreciation	(5,808,012)	(5,584,017)
Property and equipment, net	800,723	1,074,710
Laboratory and Manufacturing Equipment [Member]
Significant Accounting Policies [Line Items]
Property and equipment, Gross	3,785,133	3,734,044
Office Furniture and Equipment [Member]
Significant Accounting Policies [Line Items]
Property and equipment, Gross	688,952	701,557
Computer Equipment [Member]
Significant Accounting Policies [Line Items]
Property and equipment, Gross	1,472,144	1,563,177
Leasehold Improvements [Member]
Significant Accounting Policies [Line Items]
Property and equipment, Gross	$ 662,506	$ 659,949