Acquisitions (Schedule of Purchase Price Allocation for Acquisitions) (Detail) (USD $) In Millions, unless otherwise specified	Sep. 30, 2012 XPO And EDGAR Online Acquisitions [Member]	Dec. 31, 2011 Genesis Libre Digital Sequence Helium and Journalism Online Acquisitions [Member]
Business Acquisition [Line Items]
Accounts receivable	$ 15.4	$ 6.0
Inventories		2.3
Prepaid expenses and other current assets	0.8	0.4
Property, plant and equipment	2.2
Property, plant and equipment and other noncurrent assets		16.8
Amortizable other intangible assets	24.2	16.2
Other noncurrent assets	14.0
Goodwill	44.4	117.6
Accounts payable and accrued liabilities	(16.3)	(8.2)
Other noncurrent liabilities	(0.1)	(2.9)
Deferred taxes-net	10.4	14.2
Total purchase price-net of cash acquired	95.0	162.4
Less: debt assumed	1.4
Less: fair value of Company's previously held investments in Helium		13.9
Less: fair value of contingent consideration	3.5	6.8
Net cash paid	$ 90.1	$ 141.7