Derivatives - Schedule of Information Relating to Gain (Loss) Recognized on Swap Agreements (Detail) - USD ($) $ in Thousands	6 Months Ended
Jun. 30, 2015	Jun. 30, 2014
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Swap agreements gain (loss) recognized in OCI	$ (5,458)	$ (12,924)
Swap agreements gain (loss) reclassified from OCI - Interest expense	$ (4,933)	$ (4,610)

Amount of unrealized gain (loss) related to the increase or decrease in fair value of interest rate derivatives designated as cash flow hedging instruments, which was recorded in accumulated other comprehensive income to the extent that the cash flow hedge was determined to be effective.

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=56946850&loc=SL5624171-113959

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