Net Income (Loss) Per Share - Reconciliation of Numerator and Denominator of Basic and Diluted Net Income (Loss) Per Share (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
Mar. 31, 2015	Mar. 31, 2014
Numerator
Net income (loss)	$ 21,198us-gaap_NetIncomeLoss	$ (3,991)us-gaap_NetIncomeLoss
Denominator
Weighted average shares outstanding, basic	134,777	136,795
Effect of dilutive potential common shares	4,456
Weighted average shares outstanding, diluted	139,233	136,795
Basic net income (loss) per share	$ 0.16us-gaap_EarningsPerShareBasic	$ (0.03)us-gaap_EarningsPerShareBasic
Diluted net income (loss) per share	$ 0.15us-gaap_EarningsPerShareDiluted	$ (0.03)us-gaap_EarningsPerShareDiluted
Antidilutive employee stock-based awards, excluded	3,870	5,855

Net Income (Loss) Per Share - Reconciliation of Numerator and Denominator of Basic and Diluted Net Income (Loss) Per Share (Details) (USD $)
In Thousands, except Per Share data, unless otherwise specified

3 Months Ended

Mar. 31, 2015

Mar. 31, 2014

Numerator

Net income (loss)

$ 21,198us-gaap_NetIncomeLoss

$ (3,991)us-gaap_NetIncomeLoss

Denominator

Weighted average shares outstanding, basic

134,777us-gaap_WeightedAverageNumberOfSharesOutstandingBasic

136,795us-gaap_WeightedAverageNumberOfSharesOutstandingBasic

Effect of dilutive potential common shares

4,456us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements

Weighted average shares outstanding, diluted

139,233us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding

136,795us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding

Basic net income (loss) per share

$ 0.16us-gaap_EarningsPerShareBasic

$ (0.03)us-gaap_EarningsPerShareBasic

Diluted net income (loss) per share

$ 0.15us-gaap_EarningsPerShareDiluted

$ (0.03)us-gaap_EarningsPerShareDiluted

Antidilutive employee stock-based awards, excluded

3,870us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount

5,855us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount

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Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented.

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The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period.

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- Definition

The amount of net income (loss) for the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.

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Additional shares included in the calculation of diluted EPS as a result of the potentially dilutive effect of share based payment arrangements using the treasury stock method.

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The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

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- Definition

The average number of shares or units issued and outstanding that are used in calculating diluted EPS or earnings per unit (EPU), determined based on the timing of issuance of shares or units in the period.

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