Valuation Techniques, Significant Unobservable Inputs, and Quantitative Information (Detail) (Fair Value, Inputs, Level 3, USD $) In Millions, unless otherwise specified	3 Months Ended						3 Months Ended				3 Months Ended
	Mar. 31, 2012 Auction Rate Securities Group One	Mar. 31, 2012 Auction Rate Securities Group Two	Mar. 31, 2012 Auction Rate Securities Lower Limit Year	Mar. 31, 2012 Auction Rate Securities Upper Limit Year	Mar. 31, 2012 Contingent Consideration	Mar. 31, 2011 Contingent Consideration	Mar. 31, 2012 Contingent Consideration Group One	Mar. 31, 2012 Contingent Consideration Group Two	Mar. 31, 2012 Contingent Consideration Lower Limit	Mar. 31, 2012 Contingent Consideration Upper Limit	Mar. 31, 2012 Standby Letters of Credit
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Valuation Technique	Discounted Cash Flow						Discounted Cash Flow				Market Approach
Financial instrument discount rate			3.00%	9.00%	10.50%	10.50%
Unobservable Input	Remaining lives	Discount rates					Discount rates	Business growth rates			Market fees
Financial instrument remaining lives			2.4	8.6
Financial instrument business growth rates									1.00%	10.00%
Unamortized fees											$ 50.1