| **Derivatives - Additional Information (Detail)**                       | Mar. 31, 2013Derivatives |
|-------------------------------------------------------------------------|--------------------------|
| **Derivative Instruments and Hedging Activities Disclosure [Abstract]** |                     |
| Number of interest rate swaps                                           | 11                       |

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| - Details**Name:**us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosureAbstract**Namespace Prefix:**us-gaap_**Data Type:**xbrli:stringItemType**Balance Type:**na**Period Type:**duration |
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| - Definition
Number of interest rate derivative instruments held by the entity at the reporting date.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 1A -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=7476318&loc=SL5579245-113959Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 1B -URI http://asc.fasb.org/extlink&oid=7476318&loc=SL5580258-113959
+ Details**Name:**us-gaap_NumberOfInterestRateDerivativesHeld**Namespace Prefix:**us-gaap_**Data Type:**xbrli:integerItemType**Balance Type:**na**Period Type:**instant |