Assets and Liabilities Measured at Fair Value on a Recurring Basis (Detail) (USD $)	Mar. 31, 2013	Mar. 31, 2012	Mar. 31, 2013 Fair Value, Measurements, Recurring Fair Value, Inputs, Level 1 [Member]	Dec. 31, 2012 Fair Value, Measurements, Recurring Fair Value, Inputs, Level 1 [Member]	Mar. 31, 2013 Fair Value, Measurements, Recurring Significant Other Observable Inputs (Level 2)	Mar. 31, 2012 Fair Value, Measurements, Recurring Significant Other Observable Inputs (Level 2)	Mar. 31, 2013 Fair Value, Measurements, Recurring Fair Value, Inputs, Level 3 [Member]	Dec. 31, 2012 Fair Value, Measurements, Recurring Fair Value, Inputs, Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest Rate Derivative Assets, at Fair Value	$ 274,000	$ 288,000	$ 0	$ 0	$ 274,000	$ 288,000	$ 0	$ 0
Derivative financial instruments, Liability	$ 17,313,000	$ 21,423,000	$ 0	$ 0	$ 17,313,000	$ 21,423,000	$ 0	$ 0

Fair value as of the balance sheet date of interest rate derivative liabilities, which includes all such derivative instruments in hedging and nonhedging relationships that are recognized as liabilities.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 825

-SubTopic 10

-Section 50

-Paragraph 10

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=7491637&loc=d3e13433-108611

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 107

-Paragraph 10

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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