Fair Value of Financial Instruments - Additional Information (Detail) (USD $)		12 Months Ended				12 Months Ended					12 Months Ended
	Dec. 31, 2013 Level 2 [Member]	Dec. 31, 2013 Embedded derivative financial instruments	Jan. 24, 2013 Embedded derivative financial instruments Early Conversion Payment [Member]	Dec. 31, 2013 Fair Value, Measurements, Nonrecurring [Member]	Dec. 31, 2012 Fair Value, Measurements, Nonrecurring [Member]	Dec. 31, 2013 Fair Value, Measurements, Recurring [Member]	Dec. 31, 2012 Fair Value, Measurements, Recurring [Member]	Dec. 31, 2011 Fair Value, Measurements, Recurring [Member]	Dec. 31, 2013 Fair Value, Measurements, Recurring [Member] Level 2 [Member]	Dec. 31, 2012 Fair Value, Measurements, Recurring [Member] Level 2 [Member]	Dec. 31, 2013 Derivative Liability
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Assets, fair value disclosure				$ 0	$ 0	$ 134,096,000	$ 146,797,000		$ 118,413,000	$ 119,019,000
Liabilities, fair value disclosure				0	0	6,602,000
Impairment charges relating to available-for-sale securities						0	0	0
Conversion price of per principal amount			83.33
Principal amount of convertible notes, denominator		1,000	1,000
Conversion rate of convertible note into shares of common stock		121.1240
Conversion price of per share		$ 8.26
Fair value as of a reporting date											2,800,000
Unrealized loss of change in fair value											4,406,000
Change in fair value recorded as a loss (gain) from change in fair value of financial liability											1,616,000
Estimated fair value Notes	$ 117,700,000