Borrowings - Additional Information (Detail) (USD $)	1 Months Ended			12 Months Ended		0 Months Ended	12 Months Ended			0 Months Ended	1 Months Ended	0 Months Ended		1 Months Ended	12 Months Ended	0 Months Ended					0 Months Ended			1 Months Ended			2 Months Ended	12 Months Ended		1 Months Ended
	Jul. 31, 2013	Dec. 31, 2013	Nov. 30, 2012	Dec. 31, 2013 Silver Creek [Member]	Dec. 31, 2012 Silver Creek [Member]	Nov. 30, 2012 Loan and Security Agreement [Member]	Dec. 31, 2013 Loan and Security Agreement [Member]	Dec. 31, 2012 Loan and Security Agreement [Member]	Nov. 30, 2012 Loan and Security Agreement [Member] Hercules [Member]	Nov. 30, 2012 Second Alternative Interest Rate [Member] Loan and Security Agreement [Member]	Jul. 31, 2013 Minimum [Member]	Jul. 31, 2013 Minimum [Member] Loan and Security Agreement [Member]	Jul. 31, 2013 4.50% Convertible Senior Notes [Member]	Jul. 31, 2013 4.50% Convertible Senior Notes [Member]	Dec. 31, 2013 4.50% Convertible Senior Notes [Member]	Jul. 31, 2013 4.50% Convertible Senior Notes [Member] Conversion Terms, Fundamental Changes [Member]	Jul. 31, 2013 4.50% Convertible Senior Notes [Member] Conversion Terms, Event of Default [Member]	Jul. 31, 2013 4.50% Convertible Senior Notes [Member] Minimum [Member]	Jul. 31, 2013 4.50% Convertible Senior Notes [Member] Maximum [Member]	Dec. 31, 2013 Silver Creek Convertible Note [Member]	Dec. 31, 2013 Silver Creek Convertible Note [Member] Silver Creek [Member]	Feb. 28, 2013 Silver Creek Convertible Note [Member] Silver Creek [Member]	Dec. 31, 2012 Silver Creek Convertible Note [Member] Silver Creek [Member]	Dec. 31, 2013 Silver Creek Convertible Note [Member] Silver Creek [Member]	Feb. 28, 2013 Silver Creek Convertible Note [Member] Silver Creek [Member]	Dec. 31, 2012 Silver Creek Convertible Note [Member] Silver Creek [Member]	Feb. 28, 2013 Silver Creek Convertible Note [Member] Silver Creek [Member]	Dec. 31, 2013 Silver Creek Convertible Note [Member] Silver Creek [Member]	Dec. 31, 2012 Silver Creek Convertible Note [Member] Silver Creek [Member]	Dec. 31, 2012 Silver Creek Convertible Note [Member] Minimum [Member] Silver Creek [Member]
Schedule Of Debt Instruments [Line Items]
Aggregate principal amounts														$ 125,000,000							$ 600,000	$ 300,000	$ 1,600,000	$ 2,500,000	$ 2,500,000	$ 2,500,000	$ 300,000	$ 600,000	$ 1,600,000
Proceeds from issuance of convertible senior notes, net														120,600,000
Interest rate (as a percent)		4.50%											4.50%	4.50%	4.50%								6.00%			6.00%			6.00%
Number of days within 30 consecutive trading days in which the closing price of the entity's common stock must exceed the conversion price for the notes to be convertible																		20 days
Number of consecutive trading days during which the closing price of the entity's common stock must exceed the conversion price for at least 20 days in order for the notes to be convertible													30 days
Convertibility of debt, closing price of stock test, percentage of stock price to conversion price that must be exceeded													130.00%
Number of consecutive business days immediately after any five consecutive trading day period during the note measurement period													5 days
Number of consecutive trading days before five consecutive business days during the note measurement period													5 days
Conversion ratio, principal amount													1,000	1,000
Convertibility of debt, trading price of debt test, percentage of closing price of stock used in calculation																			98.00%
Conversion rate of common stock shares per $1,000 principal amount													160
Initial conversion price of shares (in dollars per share)													$ 6.25	$ 6.25
Premium over public offering price (as a percent)													25.00%
Public offering price (in dollars per share)	$ 5.00
Redemption price as percentage of principal amount of notes plus accrued and unpaid interest																100.00%
Minimum percentage of aggregate principal amount held by bondholders to declare notes due and payable													25.00%
Percentage of principal amount due and payable upon event of default													100.00%
Percentage of principal amount due and payable upon event of default arising out of certain bankruptcy events																	100.00%
Effective interest rate used to compute initial fair value (as a percent)													15.00%
Fair value of indebtedness													71,200,000	71,200,000
Embedded conversion option													53,800,000	53,800,000
Underwriting discounts and commissions and offering expenses													4,400,000
Debt issuance costs allocated to unamortized debt discount													2,500,000	2,500,000
Debt issuance costs attributable to embedded conversion option													1,900,000	1,900,000
Interest expense							4,900,000	600,000							6,200,000
Aggregate principal amount of loans received		125,000,000							40,000,000						125,000,000						600,000	300,000	1,600,000	600,000	300,000	1,600,000	300,000	600,000	1,600,000
Minimum stated percentage rate (as a percent)										10.55%
Stated percentage used as basis for calculation of alternative interest rate										10.55%
Description of reference rate that is added to stated percentage rate in calculation of variable rate										The term loans bear interest at an annual rate equal to the greater of 10.55% and 10.55% plus the prime rate of interest minus 5.25%, but may not exceed 12.55%
Percentage points subtracted from alternative interest rate										5.25%
Maximum interest rate on term loan (as a percent)										12.55%
Discount on loans related to costs reimbursed by the entity			39,600,000
Period of interest-only payment							12 months
Amount of gross proceeds in one or more transactions prior to December 1, 2013 that the Company may elect to extend the interest-only period by six months												75,000,000
Extension period for interest-only payment							6 months
Shares of common stock sold to public	5,750,000
Net proceeds from underwritten public offering and issuance of debt											75,000,000
Value of the Company's equity securities available for purchase by the lender						1,000,000
Period to purchase equity securities sold to institutional accredited investors under the Loan Agreement						1 year
Discount on loan recorded as a non-current liability to be paid upon full repayment or maturity of the loans							1,200,000
Less unamortized discount															52,422,000					1,600,000
Amount of gross proceeds from qualifying equity financing in which holders would automatically convert into the next qualifying equity financing at a 25% discount																														4,000,000
Discount on automatic conversion into the next qualifying equity financing (as a percent)																							25.00%			25.00%			25.00%
Derivative liability																					0		196,000	0		196,000		0	196,000
Accrued interest expense				100,000																	100,000			100,000				100,000
Ownership interest (as a percent)				64.00%	74.00%
Non-controlling interest				$ 800,000