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Represents the total fair value of nonvested equity stock units granted during the period.

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Represents the estimated period of time over which an employee is required to provide service in exchange for the equity-based payment award.

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Represents the total fair value of options for granted during the period.

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The cash inflow associated with the amount received from holders exercising their stock options. This item inherently excludes any excess tax benefit, which the entity may have realized and reported separately.

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The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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The number of non-vested equity-based payment instruments, excluding stock (or unit) options, that validly exist and are outstanding as of the balance sheet date.

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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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The weighted average fair value of nonvested awards on equity-based plans excluding option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, revenue or profit achievement stock award plan) for which the employer is contingently obligated to issue equity instruments or transfer assets to an employee who has not yet satisfied service or performance criteria necessary to gain title to proceeds from the sale of the award or underlying shares or units.

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The number of equity-based payment instruments, excluding stock (or unit) options, that vested during the reporting period.

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The weighted average fair value as of grant date pertaining to an equity-based award plan other than a stock (or unit) option plan for which the grantee gained the right during the reporting period, by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash in accordance with the terms of the arrangement.

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The estimated dividend rate (a percentage of the share price) to be paid (expected dividends) to holders of the underlying shares over the option's term.

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The period of time an equity-based award is expected to be outstanding. An equity-based award's expected term is generally determined based on, among other factors, the instrument's contractual term and the effects of employees' expected exercise and post-vesting employment termination behavior.

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The maximum period of time an equity-based award is expected to be outstanding. An equity-based award's expected term is generally determined based on, among other factors, the instrument's contractual term and the effects of employees' expected exercise and post-vesting employment termination behavior.

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The minimum period of time an equity-based award is expected to be outstanding. An equity-based award's expected term is generally determined based on, among other factors, the instrument's contractual term and the effects of employees' expected exercise and post-vesting employment termination behavior.

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The estimated measure of the percentage by which a share price is expected to fluctuate during a period. Volatility also may be defined as a probability-weighted measure of the dispersion of returns about the mean. The volatility of a share price is the standard deviation of the continuously compounded rates of return on the share over a specified period. That is the same as the standard deviation of the differences in the natural logarithms of the stock prices plus dividends, if any, over the period.

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The estimated measure of the maximum percentage by which a share price is expected to fluctuate during a period. Volatility also may be defined as a probability-weighted measure of the dispersion of returns about the mean. The volatility of a share price is the standard deviation of the continuously compounded rates of return on the share over a specified period. That is the same as the standard deviation of the differences in the natural logarithms of the stock prices plus dividends, if any, over the period.

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The risk-free interest rate assumption that is used in valuing an option on its own shares.

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The maximum risk-free interest rate assumption that is used in valuing an option on its own shares.

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The minimum risk-free interest rate assumption that is used in valuing an option on its own shares.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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The difference between the maximum number of shares (or other type of equity) authorized for issuance under the plan (including the effects of amendments and adjustments), and the sum of: 1) the number of shares (or other type of equity) already issued upon exercise of options or other equity-based awards under the plan; and 2) shares (or other type of equity) reserved for issuance on granting of outstanding awards, net of cancellations and forfeitures, if applicable.

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The total accumulated difference between fair values of underlying shares on dates of exercise and exercise price on options which were exercised (or share units converted) into shares during the reporting period under the plan.

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

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The weighted average grant-date fair value of options granted during the reporting period as calculated by applying the disclosed option pricing methodology.

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Number of shares issued during the period as a result of an employee stock purchase plan.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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-Name Regulation S-X (SX)
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-Section 02
-Paragraph 29, 30
-Article 5

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Equity Incentive Plans and Stock-Based Compensation (Details 3) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010	Dec. 31, 2010
Valuation assumptions
Dividend yield (as a percent)	0.00%	0.00%	0.00%	0.00%	0.00%
Stock Option Plans
Stock-Based Compensation
Stock option granted (in shares)	78,510	138,350	1,712,211	1,725,323
Estimated total grant date fair value	$ 0.6	$ 2.0	$ 18.3	$ 22.9
Stock-based compensation	5.0	6.0	10.2	11.7
Unrecognized compensation cost net of expected forfeitures	40.4		40.4
Expected weighted-average period for recognition of compensation cost (in years)			3.4
Total fair value of shares vested	141.7		141.7
Total intrinsic value of options exercised	1.9	3.3	4.0	5.2
Net proceeds from employee stock option			4.9
Valuation assumptions
Dividend yield (as a percent)	0.00%	0.00%	0.00%	0.00%	0.00%
Expected stock price volatility (as a percent)	50.00%	69.00%
Expected stock price volatility rate minimum (as a percent)			50.00%	61.00%
Expected stock price volatility rate maximum (as a percent)			52.00%	69.00%
Risk free interest rate (as a percent)	2.60%	3.20%
Risk free interest rate minimum (as a percent)			2.60%	2.40%
Risk free interest rate maximum (as a percent)			2.80%	3.20%
Expected term (in years)	6.1	6.1
Expected term, minimum (in years)			6.0	5.9
Expected term, maximum (in years)			6.1	6.1
Weighted-average fair value of stock options granted (in dollars per share)	$ 8.58	$ 14.38	$ 10.71	$ 13.27
Employee Stock Purchase Plans
Stock-Based Compensation
Shares issued under employee stock purchase plans (in shares)			146,034	161,293
Price per share of shares issued (in dollars per share)			$ 16.50	$ 13.56
Shares available for issuance (in shares)	439,734		439,734
Shares issued at discount from the fair market value (as a percent)			15.00%
Stock-based compensation	0.4	0.4	0.8	0.9
Unrecognized compensation cost net of expected forfeitures	0.6		0.6
Expected weighted-average period for recognition of compensation cost (in years)				0.333
Valuation assumptions
Dividend yield (as a percent)	0.00%	0.00%	0.00%	0.00%	0.00%
Expected stock price volatility (as a percent)	56.00%	54.00%	56.00%	54.00%
Risk free interest rate (as a percent)	0.10%	0.30%	0.10%	0.30%
Expected term (in years)	0.5	0.5	0.5	0.5
Weighted-average fair value of purchase rights granted under the purchase plan (in dollars per share)	$ 5.96	$ 7.46	$ 5.96	$ 7.46
Weighted-Average Grant-Date Fair Value
Granted (in dollars per share)	$ 5.96	$ 7.46	$ 5.96	$ 7.46
Shares including nonvested equity stock and stock units
Stock-Based Compensation
Stock-based compensation	1.6	1.5	3.3	3.1
Unrecognized compensation cost net of expected forfeitures	9.7		9.7
Expected weighted-average period for recognition of compensation cost (in years)			1.9
Valuation assumptions
Weighted-average fair value of purchase rights granted under the purchase plan (in dollars per share)			$ 20.86
General nonvested equity stock service period (in years)			4
Nonvested equity stock service period for directors (in years)			1
Non vested equity stock granted fair value	$ 4.5
Nonvested equity stock and stock units
Nonvested at the beginning of the period (in shares)			718,007
Granted (in shares)			213,554
Vested (in shares)			(147,197)
Forfeited (in shares)			(14,934)
Nonvested at the end of the period (in shares)	769,430		769,430
Weighted-Average Grant-Date Fair Value
Nonvested at the beginning of the period (in dollars per share)			$ 18.23
Granted (in dollars per share)			$ 20.86
Vested (in dollars per share)			$ 17.30
Forfeited (in dollars per share)	$ 21.76		$ 21.76
Nonvested at the end of the period (in dollars per share)	$ 19.07		$ 19.07