Other Employee Benefit Plans Other Employee Benefit Plans (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Compensation and Retirement Disclosure [Abstract]
401(k) matching contributions	$ 7.5	$ 4.9	$ 4.4
Pension liability	$ 9.4	$ 7.6

This represents the entire liability recognized in the balance sheet that is associated with the defined benefit plans.

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+ Details