Goodwill and Other Intangible Assets, Goodwill by Reporting Unit (Details) (USD $) In Millions, unless otherwise specified	Jun. 30, 2013		Dec. 31, 2012
Goodwill [Line Items]
Goodwill	$ 1,043.3	[1]	$ 1,041.3	[1]
Intangible Assets, Future Amortization Expense by Fiscal Year [Abstract]
Estimated amortization expense, remainder of the current fiscal year	16.6
Estimated amortization expense, 2014	28.3
Estimated amortization expense, 2015	25.0
Estimated amortization expense, 2016	21.6
Estimated amortization expense, 2017	19.3
Estimated amortization expense, 2018	17.4
United States [Member]
Goodwill [Line Items]
Goodwill	504.0		504.0
France [Member]
Goodwill [Line Items]
Goodwill	82.7		83.8
Netherlands (Vitae) [Member]
Goodwill [Line Items]
Goodwill	79.6		80.7
Right Management [Member]
Goodwill [Line Items]
Goodwill	62.1		62.1
Other reporting units [Member]
Goodwill [Line Items]
Goodwill	$ 314.9		$ 310.7

[1] Balances were net of accumulated impairment loss of $513.4 as of both June 30, 2013 and December 31, 2012.