Derivative Instruments and Hedging Activities - Fair Value of Company's Derivative Financial Instruments Classification on Unaudited Condensed Consolidated Balance Sheets (Detail) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Derivatives Fair Value [Line Items]
Liability Derivatives Fair Value	$ 16,639	$ 22,808
Other Liabilities [Member]
Derivatives Fair Value [Line Items]
Liability Derivatives Fair Value	16,639	22,808
Interest Rate Swaps [Member] | Other Liabilities [Member]
Derivatives Fair Value [Line Items]
Liability Derivatives Fair Value	$ 16,639	$ 22,808