Long-term Debt - Additional Information (Detail) (USD $) Share data in Millions, except Per Share data, unless otherwise specified	6 Months Ended	0 Months Ended		6 Months Ended		0 Months Ended			0 Months Ended	6 Months Ended			0 Months Ended	6 Months Ended
	Jun. 30, 2014	Jun. 12, 2014 Convertible Note Hedge	Jun. 12, 2014 Convertible Note Hedge	Jun. 30, 2014 Convertible Note	Jun. 30, 2014 Convertible Note Default Event	Jun. 12, 2014 Convertible Note Warrant	Jun. 30, 2014 Convertible Note Warrant	Jun. 12, 2014 Convertible Note Warrant	Jun. 17, 2014 Senior Notes	Jun. 30, 2014 Senior Notes PrincipalAmount	Jun. 17, 2014 Senior Notes	Jun. 11, 2014 Senior Notes	Jun. 17, 2014 Senior Notes Convertible Note Hedge	Jun. 30, 2014 Senior Notes Equity Component	Jun. 30, 2014 Senior Notes Liability Component	Jun. 30, 2014 Bank term loan	Jun. 30, 2014 Bank term loan Minimum	Jun. 30, 2014 Bank term loan Maximum
Debt Instrument [Line Items]
Debt instrument, principal amount			$ 200,000,000					$ 200,000,000		$ 200,000,000	$ 200,000,000
Net proceeds from issuance of convertible notes	194,000,000								192,900,000				43,200,000
Fees related to debt											6,000,000
Cost and expense related to debt									1,100,000	1,100,000				254,000	825,000
Debt instrument, interest rate	3.625%									3.625%
Bank term loan, frequency of payments of principal and interest										Semi-annually						The bank term loan provided for quarterly payments of principal and interest with final scheduled maturity on December 31, 2015.
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						Dec. 31, 2015
Initial conversion rate, shares per $1,000										107.5095
Exercise price of shares covered by note hedge transactions			$ 9.30							$ 9.30
Conversion premium percentage										32.50%
Sale price of common stock												$ 7.02
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% 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% 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 the option of the holder regardless of the foregoing circumstances.
Repurchase price of principal amount										100.00%
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
Interest expenses amortization period										5 years
Expected life of debt										5 years
Carrying value of convertible notes										153,119,000
Debt instruments, effective interest rate															9.60%
Number of shares		21.5
Convertible note hedge transactions, reduction to additional paid-in capital		(43,200,000)
Number of shares						21.5
Exercise price of shares issued on warrant transactions							$ 12.00	$ 12.00
Percentage of exercise price above the last reported sale price of common stock								70.00%
Proceeds from issuance of warrants	27,580,000					27,600,000
Bank term loan, interest rate over and above LIBOR																	1.25%	2.25%
Bank term loan, required minimum in unrestricted cash, cash equivalents and investments																	$ 15,000,000