Reconciliation for Liabilities Measured at Fair Value on Recurring Basis using Significant Unobservable Inputs (Level Three) (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012		Dec. 31, 2011
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	$ 5,000		$ 5,700
Income (Expense) Realized in Earnings	(1,350)		4,178
Transfers In/Out of Level 3	(4,000)
Purchases			3,478
Issuances
Settlements
Ending Balance	2,350		5,000
Contingent consideration
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	3,597	[1]
Income (Expense) Realized in Earnings	(403)	[1]	(119)
Transfers In/Out of Level 3	(4,000)	[1]
Purchases			3,478
Issuances		[1]
Settlements		[1]
Ending Balance			3,597	[1]
Common stock warrant liability
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	1,403		5,700
Income (Expense) Realized in Earnings	(947)		4,297
Issuances
Settlements
Ending Balance	$ 2,350		$ 1,403

[1] Contingent consideration transferred out of Level 3 at December 31, 2012 as a result of the final computation of the contingent consideration under the terms of the purchase agreement. With the resolution of the contingency, this liability is no longer measured at fair value.