Derivative Financial Instruments - Effect of Derivative Instruments on Condensed Consolidated Statements of Income Derivative in Cash Flow Hedging Relationship (Detail) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2018	Mar. 31, 2017
Cash Flow Hedging [Member] \| Interest Rate Contracts One [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Comprehensive Income on Derivative (Effective Portion)	$ 358	$ 260

The effective portion of gains and losses (net) on derivative instruments designated and qualifying as hedging instruments that was recognized in other comprehensive income during the current period.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4C
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=84234895&loc=SL5624171-113959

Name:	us-gaap_DerivativeInstrumentsGainLossRecognizedInOtherComprehensiveIncomeEffectivePortionNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration