Derivative Financial Instruments - Additional Information (Detail)	12 Months Ended
Dec. 31, 2017 USD ($)
Other Income (Expense) [Member]
Derivatives Fair Value [Line Items]
Gain (loss) on discontinuance of cash flow hedges	$ 0
Maximum [Member]
Derivatives Fair Value [Line Items]
Derivative instruments maturity term	12 months

The amount of net gain (loss) reclassified into earnings in the period when cash flow hedge is discontinued because it is probable that the original forecasted transactions will not occur by the end of the original period or an additional two month time period.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 30
-Section 50
-Paragraph 1
-Subparagraph (e)
-URI http://asc.fasb.org/extlink&oid=35736893&loc=d3e80748-113994

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