Fair Value Measurement - Reconciliation of the Beginning and Ending Level 3 Net Liabilities (Detail) (Significant Unobservable Inputs (Level 3) [Member], Contingent Earnout Consideration [Member], USD $) In Thousands, unless otherwise specified	9 Months Ended	12 Months Ended
	Sep. 30, 2013	Dec. 31, 2012
Significant Unobservable Inputs (Level 3) [Member] | Contingent Earnout Consideration [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance		$ 231
Change in fair value related to Meridian contingent earnout consideration		(231)
Ending balance