Long-term Debt - Additional Information (Detail) (USD $) Share data in Millions, except Per Share data, unless otherwise specified	12 Months Ended	0 Months Ended
	Dec. 31, 2014	Jun. 12, 2014	Jun. 17, 2014	Nov. 01, 2013	Feb. 25, 2009	Jun. 11, 2014
Debt Instrument [Line Items]
Net proceeds from issuance of convertible notes	$ 192,921,000
Cost and expense related to debt	7,079,000
Exercise price of shares issued on warrant transactions				$ 20.00	$ 2.15
Proceeds from issuance of warrants	27,580,000
Convertible Note Hedge
Debt Instrument [Line Items]
Debt instrument, principal amount		200,000,000
Exercise price of shares covered by note hedge transactions		$ 9.30
Number of shares		21.5
Convertible note hedge transactions, reduction to additional paid-in capital		(43,200,000)
Convertible Note
Debt Instrument [Line Items]
Debt instrument conversion description	At any time prior to the close of business on the business day immediately preceding December 15, 2018, holders may convert their convertible notes at their option only under the following circumstances: • during any calendar quarter commencing after the calendar quarter ending on December 31, 2014 (and only during such calendar quarter), if the last reported sale price of our common stock for at least 20 trading days (whether or not consecutive) during a period of 30 consecutive trading days ending on the last trading day of the immediately preceding calendar quarter is greater than or equal to 130 percent of the conversion price, or approximately $12.00 per share, on each applicable trading day; •during the five business day period after any five consecutive trading day period, or the measurement period, in which the trading price per $1,000 principal amount of the convertible notes for each trading day of the measurement period was less than 98 percent of the product of the last reported sale price of the Company’s common stock and the conversion rate on each such trading day; or • upon the occurrence of specified corporate events. On or after December 15, 2018 until the close of business on the second scheduled trading day immediately preceding the maturity date, holders may convert all or any portion of their convertible notes, in multiples of $1,000 principal amount, at their option regardless of the foregoing circumstances.
Convertible Note | Default Event
Debt Instrument [Line Items]
Minimum percentage of principal amount of outstanding to declare	25.00%
Percentage of principal outstanding payable at event of default	100.00%
Period to resolve default of event	180 days
Convertible Note Warrant
Debt Instrument [Line Items]
Debt instrument, principal amount		200,000,000
Number of shares		21.5
Exercise price of shares issued on warrant transactions		$ 12.00
Percentage of exercise price above the last reported sale price of common stock		70.00%
Proceeds from issuance of warrants		27,600,000
Senior Notes
Debt Instrument [Line Items]
Debt instrument, principal amount	200,000,000		200,000,000
Net proceeds from issuance of convertible notes			192,900,000
Fees related to debt			6,000,000
Cost and expense related to debt	1,100,000		1,100,000
Debt instrument, interest rate	3.625%
Bank term loan, frequency of payments of principal and interest	Semi-annually
Debt instrument, interest payable date	--06-15
Debt instrument, interest payable date	--12-15
Debt instrument, interest payment start date	Dec. 15, 2014
Bank term loan, maturity date	Jun. 15, 2019
Initial conversion rate, shares per $1,000	107.5095
Exercise price of shares covered by note hedge transactions	$ 9.30
Conversion premium percentage	32.50%
Sale price of common stock						$ 7.02
Repurchase price of principal amount	100.00%
Interest expenses amortization period	5 years
Interest expenses remaining amortization period	53 years 6 months
Expected life of debt	5 years
Senior Notes | Convertible Note Hedge
Debt Instrument [Line Items]
Net proceeds from issuance of convertible notes			43,200,000
Senior Notes | Equity Component
Debt Instrument [Line Items]
Cost and expense related to debt	254,000
Senior Notes | Liability Component
Debt Instrument [Line Items]
Cost and expense related to debt	825,000
Debt instruments, effective interest rate	9.625%
Bank term loan
Debt Instrument [Line Items]
Bank term loan, frequency of payments of principal and interest	The bank term loan provided for quarterly payments of principal and interest with final scheduled maturity on December 31, 2015.
Bank term loan, maturity date	Dec. 31, 2015
Bank term loan | Minimum
Debt Instrument [Line Items]
Bank term loan, interest rate over and above LIBOR	1.25%
Bank term loan, required minimum in unrestricted cash, cash equivalents and investments	$ 15,000,000
Bank term loan | Maximum
Debt Instrument [Line Items]
Bank term loan, interest rate over and above LIBOR	2.25%