Valuation Technique and Inputs Used to Determine Fair Value of Assets Or Liabilities (Detail)	3 Months Ended
	Mar. 31, 2013
Discount Rate
Fair Value Assets And Liabilities Measured On Unobservable Inputs [Line Items]
Contingent consideration, weighted average	6.00%
Discount Rate | Minimum
Fair Value Assets And Liabilities Measured On Unobservable Inputs [Line Items]
Contingent consideration	2.00%
Discount Rate | Maximum
Fair Value Assets And Liabilities Measured On Unobservable Inputs [Line Items]
Contingent consideration	10.00%
Probability of payment
Fair Value Assets And Liabilities Measured On Unobservable Inputs [Line Items]
Contingent consideration, weighted average	55.00%
Probability of payment | Minimum
Fair Value Assets And Liabilities Measured On Unobservable Inputs [Line Items]
Contingent consideration	0.00%
Probability of payment | Maximum
Fair Value Assets And Liabilities Measured On Unobservable Inputs [Line Items]
Contingent consideration	100.00%