Derivative Instruments and Hedging Activities - Fair Value of Company's Derivative Financial Instruments Classification in Consolidated Balance Sheet (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Derivatives Fair Value [Line Items]
Liability Derivatives Fair Value	$ 8,455	$ 22,808
Other Liabilities [Member]
Derivatives Fair Value [Line Items]
Liability Derivatives Fair Value	8,455	22,808
Interest Rate Swaps [Member] \| Other Liabilities [Member]
Derivatives Fair Value [Line Items]
Liability Derivatives Fair Value	$ 8,455	$ 22,808

Fair value as of the balance sheet date of interest rate derivative liabilities, which includes all such derivative instruments in hedging and nonhedging relationships that are recognized as liabilities.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 10
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=77997519&loc=d3e13433-108611

Name:	us-gaap_InterestRateDerivativeLiabilitiesAtFairValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant