Stock-Based Compensation (Details) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended	9 Months Ended
Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011 years productcandidate workforcereduction product segment	Sep. 30, 2010
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Recorded stock-based compensation expense	$ 2.9	$ 1.8	$ 8.4	$ 6.9
Total unrecognized compensation costs related to non-vested share-based compensation.	13.3		13.3
Weighted average period over which costs will be recognized			1.35
Common stock shares issued during period to award payment			629,816	543,460
Cash received from exercise of stock options and purchases			$ 4.0	$ 2.8
Common stock reserved for future issuance	5,171,643		5,171,643

Represents the expense recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees.

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Aggregate proceeds received by the entity during the annual period from exercises of stock or unit options and conversion of similar instruments granted under equity-based payment arrangements.

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As of the balance sheet date, the aggregate unrecognized cost of equity-based awards made to employees under equity-based compensation awards that have yet to vest.

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The weighted average period over which unrecognized compensation is expected to be recognized for equity-based compensation plans, using a decimal to express in number of years.

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

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