Contingencies (Narrative) (Details) (USD $) In Millions, unless otherwise specified	1 Months Ended	3 Months Ended	9 Months Ended	12 Months Ended		9 Months Ended	12 Months Ended		1 Months Ended	9 Months Ended
	Apr. 30, 2011	Jun. 30, 2011	Sep. 30, 2011	Dec. 31, 2009	Dec. 31, 2010	Sep. 30, 2011 Legacy Tax Matters [Member]	Dec. 31, 2009 Legacy Tax Matters IMS Health and NMR 1993 - 1996 [Member]	Sep. 30, 2011 Legacy Tax Matters Amortization Expense Deductions 2000 Distribution Agreement [Member]	May 31, 2010 Settlement of Tax Years 1997 - 2002 [Member]	Sep. 30, 2011 Settlement of Tax Years 1997 - 2002 [Member]	Dec. 31, 2006 Settlement of Tax Years 1997 - 2002 [Member]	Sep. 30, 2011 Legacy Tax Matters 1989-1990 and 1993-1996 [Member]
Loss Contingencies [Line Items]
Minimum likelihood that a tax position will be sustained based on its technical merits as of the reporting date			50.00%
Liabilities for 2000 distribution agreement and Liabilities for Legacy Tax Matters, Liability for the remaining potential exposure			$ 51.5		$ 57.3			$ 51.5				$ 53.6
Proceeds from IMS Health, NMR arbitration settlements and New D&B for 50% of the anticipated future tax benefits through 2012						55.0	10.8
Benefit to net income related to the resolution of Legacy Tax Matters							8.2
Reduction of interest expense		2.8		6.5
Reduction in interest expense, net of tax		1.7
Reduction of tax expense				4.3
Increase in other non-operating income		6.4
Liability for legacy tax matters												2
Deposit with IRS to stop the accrual of statutory interest on potential tax deficiencies with respect to the 1997 through 2002 tax years, New D&B and Moody's Commenced procedures to recover approximately			11.3		11.4						39.8
Refund from IRS for the 1997 tax year									5.2
Refund from IRS for the 1997 tax year, interest									2.5
After-tax benefit from tax settlement										4.6
Legacy Refund, net	0.6
Legacy Refund	0.9
Total legacy tax impact unusual in nature			7.0
Total legacy tax impact			$ 8.7