Loss Per Share (Details)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Number of common stock warrant and common stock options exercised	5,787,983	10,881,570	1,086,361
Number of common stock issued for stock warrant and stock options exercised	5,392,741	10,732,745	1,084,982
Shares surrendered in lieu of cash payment	426	148,825	1,379
Common stock investments, available for sale
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential common shares	28,456,149	32,105,859	26,695,436