Interest Rate Swap Agreements - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	6 Months Ended
Jun. 30, 2013 Agreement	Jun. 30, 2012
Derivative [Line Items]
Number of interest rate swap agreements	3
Changes in fair values are reclassified from accumulated other comprehensive income (loss) into earnings	$ 2,880	$ 6,263
Amortized Interest Expenses related to a previously terminated interest rate swap agreement		$ 1,976

Number of interest rate derivative instruments held by the entity at the reporting date.

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=SL5579245-113959

Reference 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

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant