Employee Benefit Plans (Details 2) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Plan Assets:
Total plan assets	$ 112.9	$ 111.3	$ 95.7
Target allocations
Bonds including cash (as a percent)	40.00%
Equity investments (as a percent)	35.00%
Real estate and mortgages (as a percent)	25.00%
Estimated Future Benefit Payments
2012	2.6
2013	3.0
2014	3.9
2015	4.1
2016	4.9
2017-2021	29.9
Other Benefit Plans
Company's contributions to defined contribution plans	3.7	2.5	2.7
Maximum
Employee Benefit Plans
Discount rate (as a percent)	5.50%	5.60%	5.90%
Expected return on plan assets (as a percent)	4.00%	4.30%	4.30%
Expected rate of compensation increase (as a percent)	3.80%	3.00%	3.00%
Minimum
Employee Benefit Plans
Discount rate (as a percent)	1.10%	1.20%	2.00%
Expected return on plan assets (as a percent)	3.40%	3.50%	3.50%
Expected rate of compensation increase (as a percent)	1.00%	1.00%	1.00%
Cash and cash equivalents
Plan Assets:
Total plan assets	8.3
Debt securities:
Plan Assets:
Total plan assets	49.4
Debt securities: Foreign corporations
Plan Assets:
Total plan assets	12.5
Debt securities: Foreign governments
Plan Assets:
Total plan assets	36.9
Equity Securities:
Plan Assets:
Total plan assets	34.6
Equity Securities: Foreign corporations
Plan Assets:
Total plan assets	28.6
Equity Securities: U.S. corporations
Plan Assets:
Total plan assets	6.0
Real estate
Plan Assets:
Total plan assets	13.9
Mortgage and other asset-backed securities
Plan Assets:
Total plan assets	6.7
Quoted Prices in Active Markets Available (Level 1)
Plan Assets:
Total plan assets	99.0
Quoted Prices in Active Markets Available (Level 1) | Cash and cash equivalents
Plan Assets:
Total plan assets	8.3
Quoted Prices in Active Markets Available (Level 1) | Debt securities:
Plan Assets:
Total plan assets	49.4
Quoted Prices in Active Markets Available (Level 1) | Debt securities: Foreign corporations
Plan Assets:
Total plan assets	12.5
Quoted Prices in Active Markets Available (Level 1) | Debt securities: Foreign governments
Plan Assets:
Total plan assets	36.9
Quoted Prices in Active Markets Available (Level 1) | Equity Securities:
Plan Assets:
Total plan assets	34.6
Quoted Prices in Active Markets Available (Level 1) | Equity Securities: Foreign corporations
Plan Assets:
Total plan assets	28.6
Quoted Prices in Active Markets Available (Level 1) | Equity Securities: U.S. corporations
Plan Assets:
Total plan assets	6.0
Quoted Prices in Active Markets Available (Level 1) | Mortgage and other asset-backed securities
Plan Assets:
Total plan assets	6.7
Significant Other Observable Inputs (Level 2)
Plan Assets:
Total plan assets	13.9
Significant Other Observable Inputs (Level 2) | Real estate
Plan Assets:
Total plan assets	$ 13.9