Financial Assets and Liabilities that are Measured At Fair Value and are Categorized Using Fair Value Hierarchy (Detail) - Fair Value, Measurements, Recurring - USD ($)	Sep. 30, 2017	Dec. 31, 2016
Interest Rate Swap [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Assets, Fair Value Disclosure, Recurring	$ 7,705,000	$ 8,842,000
Financial Liabilities		100,000
Contingent Consideration
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Financial Liabilities	2,864,000	6,612,000
Fair Value, Inputs, Level 1 [Member] | Interest Rate Swap [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Assets, Fair Value Disclosure, Recurring	0	0
Financial Liabilities		0
Fair Value, Inputs, Level 1 [Member] | Contingent Consideration
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Financial Liabilities		0
Fair Value, Inputs, Level 2 [Member] | Interest Rate Swap [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Assets, Fair Value Disclosure, Recurring	7,705,000	8,842,000
Financial Liabilities		100,000
Fair Value, Inputs, Level 2 [Member] | Contingent Consideration
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Financial Liabilities		0
Fair Value, Inputs, Level 3 [Member] | Interest Rate Swap [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Assets, Fair Value Disclosure, Recurring		0
Financial Liabilities		0
Fair Value, Inputs, Level 3 [Member] | Contingent Consideration
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Financial Liabilities	$ 2,864,000	$ 6,612,000