Fair Value of Financial Instruments - Financial Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - Fair Value, Measurements, Recurring - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Fair Value, Asset/Liability
Assets, fair value	$ 36,328	$ 14,559
Liabilities, fair value	1,454	535
Contingent consideration for business acquisitions
Fair Value, Asset/Liability
Liabilities, fair value	900	226
Interest rate swaps
Fair Value, Asset/Liability
Assets, fair value		172
Liabilities, fair value	554	309
Convertible debt investment
Fair Value, Asset/Liability
Assets, fair value	34,050	12,250
Promissory note
Fair Value, Asset/Liability
Assets, fair value	2,278	2,137
Significant Other Observable Inputs (Level 2)
Fair Value, Asset/Liability
Assets, fair value		172
Liabilities, fair value	554	309
Significant Other Observable Inputs (Level 2) | Interest rate swaps
Fair Value, Asset/Liability
Assets, fair value		172
Liabilities, fair value	554	309
Significant Unobservable Inputs (Level 3)
Fair Value, Asset/Liability
Assets, fair value	36,328	14,387
Liabilities, fair value	900	226
Significant Unobservable Inputs (Level 3) | Contingent consideration for business acquisitions
Fair Value, Asset/Liability
Liabilities, fair value	900	226
Significant Unobservable Inputs (Level 3) | Convertible debt investment
Fair Value, Asset/Liability
Assets, fair value	34,050	12,250
Significant Unobservable Inputs (Level 3) | Promissory note
Fair Value, Asset/Liability
Assets, fair value	$ 2,278	$ 2,137