Stockholders Equity - Additional Information (Detail) (USD $) Share data in Millions, unless otherwise specified	9 Months Ended			1 Months Ended
	Sep. 30, 2013	May 31, 2012	Feb. 28, 2011	Feb. 28, 2011 4.75% Convertible Notes Due Two Thousand Eighteen	May 31, 2012 Senior Convertible Notes Due 2018	May 09, 2012 Senior Convertible Notes Due 2018
Schedule of Capitalization, Equity [Line Items]
Convertible notes exchanged, warrants issued to purchase common stock					4.0
Convertible notes exchanged, warrants exercise price						1.863
Warrant liability, fair value	$ 1,600,000	$ 5,300,000
Principal amount of issued debt	1,000			230,000,000
Convertible senior notes, maturity date	May 09, 2019			Feb. 01, 2018
Conversion feature of Convertible Notes				35,600,000
Deferred tax liability set-up related to the Convertible Notes (net of finance costs)			22,700,000
Issuance costs				$ 1,900,000