CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (USD $) In Thousands, unless otherwise specified	Total	Common Stock	Additional Paid-in Capital	Accumulated Deficit	Accumulated Other Comprehensive Gain (Loss)
Balance at Dec. 31, 2011	$ 429,794us-gaap_StockholdersEquity	$ 110	$ 1,049,716	$ (619,643)	$ (389)
Balance (in shares) at Dec. 31, 2011		110,267
Net income (loss)	(134,336)us-gaap_NetIncomeLoss	0	0	(134,336)	0
Increase (Decrease) in Stockholders' Equity
Unrealized gain (loss) on marketable securities, net of tax	89	0	0	0	89
Issuance of common stock upon exercise of options, equity stock and employee stock purchase plan	3,501	2	3,499	0	0
Issuance of common stock upon exercise of options, equity stock and stock units, and employee stock purchase plan (in shares)		1,258
Stock-based compensation	22,546	0	22,546	0	0
Balance at Dec. 31, 2012	321,594us-gaap_StockholdersEquity	112	1,075,761	(753,979)	(300)
Balance (in shares) at Dec. 31, 2012		111,525
Net income (loss)	(33,748)us-gaap_NetIncomeLoss	0	0	(33,748)	0
Increase (Decrease) in Stockholders' Equity
Unrealized gain (loss) on marketable securities, net of tax	(5)	0	0	0	(5)
Issuance of common stock upon exercise of options, equity stock and employee stock purchase plan	7,865	1	7,864	0	0
Issuance of common stock upon exercise of options, equity stock and stock units, and employee stock purchase plan (in shares)		1,934
Stock-based compensation	14,981	0	14,981	0	0
Equity component of 1.125% convertible senior notes due 2018	29,542	0	29,542
Balance at Dec. 31, 2013	340,229us-gaap_StockholdersEquity	113	1,128,148	(787,727)	(305)
Balance (in shares) at Dec. 31, 2013		113,459
Net income (loss)	26,201us-gaap_NetIncomeLoss	0	0	26,201
Increase (Decrease) in Stockholders' Equity
Unrealized gain (loss) on marketable securities, net of tax	(97)	0	0	0	(97)
Issuance of common stock upon exercise of options, equity stock and employee stock purchase plan	10,559	2	10,557	0	0
Issuance of common stock upon exercise of options, equity stock and stock units, and employee stock purchase plan (in shares)		1,703
Stock-based compensation	14,730	0	14,730	0	0
Balance at Dec. 31, 2014	$ 391,622us-gaap_StockholdersEquity	$ 115	$ 1,153,435	$ (761,526)	$ (402)
Balance (in shares) at Dec. 31, 2014		115,162

Adjustment to additional paid in capital resulting from the recognition of convertible debt instruments as two separate components - a debt component and an equity component. This bifurcation may result in a basis difference associated with the liability component that represents a temporary difference for purposes of applying accounting for income taxes. The initial recognition of deferred taxes for the tax effect of that temporary difference is as an adjustment to additional paid in capital.

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