Net Loss Per Common Share (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		87 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2014
Basic and diluted net loss per common share calculation:
Net loss	$ (20,682)	$ (4,618)	$ (172,457)
Accretion of preferred stock dividends		(1,742)	(33,046)
Net loss attributable to common stockholders	$ (20,682)	$ (6,360)	$ (205,503)
Weighted average common shares outstanding	32,282	1,470
Net loss per share of common stock - basic and diluted (in dollars per share)	$ (0.64)	$ (4.33)
Anti-dilutive securities
Total (in shares)	3,814	18,256
Redeemable convertible preferred stock
Anti-dilutive securities
Total (in shares)		16,811
Options outstanding
Anti-dilutive securities
Total (in shares)	3,726	1,344
Warrants
Anti-dilutive securities
Total (in shares)	88	101