Fair Value Information - Additional Information (Detail) (USD $) In Millions, unless otherwise specified			9 Months Ended
Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014 Minimum [Member]	Sep. 30, 2014 Maximum [Member]
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]
Fair value assets transfers from Level 1 to Level 2	$ 0	$ 0
Fair value assets transfers from Level 2 to Level 1	$ 0	$ 0
Term of interest rate swap contracts by the counterparty, years			3 years	30 years

Amount of transfers of assets measured on a recurring basis out of Level 1 of the fair value hierarchy into Level 2.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 820

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (bb)

-URI http://asc.fasb.org/extlink&oid=36462937&loc=d3e19207-110258

Name:	us-gaap_FairValueAssetsLevel1ToLevel2TransfersAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant