Stock Warrants (Details) - Warrant - $ / shares	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Number of Securities Called by Warrants or Rights [Roll Forward]
Beginning balance (in shares)	0	84,000	354,546
Stock warrants granted (in shares)	0	0	0
Stock warrants expired (in shares)	0	(16,364)	0
Stock warrants exercised (in shares)	0	(67,636)	(270,546)
Ending balance (in shares)	0	0	84,000
Exercise Price of Warrants or Rights [Roll Forward]
Beginning balance (in dollars per share)	$ 0.00	$ 1.21	$ 1.21
Stock warrants granted (in dollars per share)	0.00	0.00	0.00
Stock warrants expired (in dollars per share)	0.00	1.21	0.00
Stock warrants exercised (in dollars per share)	0.00	1.21	1.21
Ending balance (in dollars per share)	$ 0.00	$ 0.00	$ 1.21