Derivative Financial Instruments - Fair Value of Derivative Instruments (Detail) (Derivatives not designated as hedging instruments [Member], USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Other Liabilities [Member]
Derivatives, Fair Value [Line Items]
Liability Derivatives	$ 13,393	$ 23,966
Other Liabilities [Member] \| Interest rate swaps [Member]
Derivatives, Fair Value [Line Items]
Liability Derivatives	13,393	23,966
Other Assets [Member]
Derivatives, Fair Value [Line Items]
Asset Derivatives	13,393	23,966
Other Assets [Member] \| Interest rate swaps [Member]
Derivatives, Fair Value [Line Items]
Asset Derivatives	$ 13,393	$ 23,966

Fair value before effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 20

-Section 55

-Paragraph 7

-URI http://asc.fasb.org/extlink&oid=28370219&loc=SL20226000-175313

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 20

-Section 50

-Paragraph 3

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=20225523&loc=SL20225862-175312

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 4B

-Subparagraph (a),(c)

-URI http://asc.fasb.org/extlink&oid=7476318&loc=SL5624163-113959

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