Stock Plans (Summary of Stock Option Activity) (Details) (USD $) In Millions, except Share data in Thousands, unless otherwise specified	6 Months Ended
Jun. 30, 2013
Stock option activity
Number of Shares, Outstanding at beginning of period	4,266
Number of Shares, Granted	518
Number of Shares, Exercised	(336)
Number of Shares, Canceled	(7)
Number of Shares, Forfeited	(299)
Number of Shares, Outstanding at end of period	4,142
Number of Shares, Exercisable at end of period	2,960
Number of Shares, Vested and expected to vest in the future	4,091
Weighted-Average Price, Outstanding at beginning of period	$ 21.64
Weighted-Average Price, Granted	$ 33.62
Weighted-Average Price, Exercised	$ 21.68
Weighted-Average Price, Canceled	$ 22.63
Weighted-Average Price, Forfeited	$ 22.39
Weighted-Average Price, Outstanding at end of period	$ 23.08
Weighted-Average Price, Exercisable at end of period	$ 20.81
Weighted-Average Price, Vested and expected to vest in the future	$ 23.02
Weighted-Average Remaining Contractual Term in Years, Outstanding at end of period	3 years 8 months
Weighted-Average Remaining Contractual Term in Years, Exercisable at end of period	2 years 10 months
Weighted-Average Remaining Contractual Term in Years, Vested and expected to vest in the future	3 years 8 months
Total Intrinsic Value, Outstanding at end of period	$ 40.4
Total Intrinsic Value, Exercisable at end of period	35.3
Total Intrinsic Value, Vested and expected to vest in the future	$ 40.2

Amount of difference between fair value of the underlying shares reserved for issuance and exercise price of vested portions of options outstanding and currently exercisable.

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The number of shares into which fully or partially vested stock options outstanding as of the balance sheet date can be currently converted under the option plan.

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The weighted-average price as of the balance sheet date at which grantees can acquire the shares reserved for issuance on vested portions of options outstanding and currently exercisable under the stock option plan.

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Weighted average remaining contractual term for vested portions of options outstanding and currently exercisable or convertible, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Number of options or other stock instruments for which the right to exercise has lapsed under the terms of the plan agreements.

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The number of shares under options that were cancelled during the reporting period as a result of occurrence of a terminating event specified in contractual agreements pertaining to the stock option plan.

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Net number of share options (or share units) granted during the period.

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Amount of difference between fair value of the underlying shares reserved for issuance and exercise price of options outstanding.

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The number of shares reserved for issuance under stock option agreements awarded under the plan that validly exist and are outstanding as of the balance sheet date, including vested options.

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Weighted average price at which grantees can acquire the shares reserved for issuance under the stock option plan.

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Weighted average remaining contractual term for option awards outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Amount of difference between fair value of the underlying shares reserved for issuance and exercise prices of fully vested and expected to vest options outstanding.

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As of the balance sheet date, the number of shares into which fully vested and expected to vest stock options outstanding can be converted under the option plan.

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As of the balance sheet date, the weighted-average exercise price for outstanding stock options that are fully vested or expected to vest.

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Weighted average price at which option holders acquired shares when converting their stock options into shares.

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Weighted average price at which grantees could have acquired the underlying shares with respect to stock options of the plan that expired.

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Number of share options (or share units) exercised during the current period.

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