Summary of Significant Accounting Policies - Antidilutive Securities Excluded from Computation of Earnings per Share (Detail)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Accounting Policies [Line Items]
Antidilutive Securities	16,099,078	15,394,961	16,682,172
Preferred Shares [Member]
Accounting Policies [Line Items]
Antidilutive Securities
Warrant [Member]
Accounting Policies [Line Items]
Antidilutive Securities	10,534,245	10,377,995	12,564,193
Employee Stock Option [Member]
Accounting Policies [Line Items]
Antidilutive Securities	5,564,833	5,016,966	4,117,979