Loss Per Common Share (Number Shares) (Details) - shares	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017	Dec. 31, 2016
Stock options outstanding	3,317,560		3,047,873
Warrants to purchase common stock	5,489,733	5,489,733	5,489,733
Stock Bonus Plan [Member]
Non-vested stock bonus plan shares	57,760	57,760	102,048	102,048