Valuation Techniques, Significant Unobservable Inputs, and Quantitative Information (Detail) (Fair Value, Inputs, Level 3, USD $) In Millions, unless otherwise specified		9 Months Ended						9 Months Ended
	Sep. 30, 2012 Auction Rate Securities	Sep. 30, 2012 Auction Rate Securities Group One	Sep. 30, 2012 Auction Rate Securities Group Two	Sep. 30, 2012 Auction Rate Securities Lower Limit Y	Sep. 30, 2012 Auction Rate Securities Upper Limit Y	Sep. 30, 2012 Contingent Consideration	Dec. 31, 2011 Contingent Consideration	Sep. 30, 2012 Contingent Consideration Group One	Sep. 30, 2012 Contingent Consideration Group Two	Sep. 30, 2012 Contingent Consideration Lower Limit	Sep. 30, 2012 Contingent Consideration Upper Limit
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Financial instrument, fair value	$ 99.5					$ 48.9
Valuation Technique		Discounted Cash Flow						Discounted Cash Flow
Unobservable Input		Remaining lives	Discount rates					Discount rates	Business growth rates
Financial instrument remaining lives				2.4	8.6
Financial instrument discount rate				0.22%	9.00%	10.50%	10.50%
Financial instrument business growth rates										19.00%	35.00%