Stockholders' Equity (Summary of Status of Nonvested Shares) (Details) - $ / shares	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Number of Options
Nonvested Shares at December 31, 2014			6,032,315
Granted			792,250
Vested			(1,288,222)
Cancelled or expired			(1,415,553)
Nonvested Shares at September 30, 2015	4,120,790		4,120,790
Weighted Average Grant- Date Fair Value (usd per share)
Nonvested Shares at December 31, 2014			$ 5.66
Granted	$ 4.10	$ 4.57	4.47	$ 4.99
Vested			5.29
Cancelled or expired			6.24
Nonvested Shares at September 30, 2015	$ 5.35		$ 5.35