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Acquisitions and Dispositions - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified | 6 Months Ended
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Jun. 30, 2013 Trust Investment | Jun. 30, 2012
Business Combinations [Abstract] |  |
Number of limited partnerships | 18 |
Number of business income trusts | 2 |
Purchase of non-controlling interests | $ (7) | $ (47)

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- Definition Number of business income trusts. + References No definition available. + Details
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- Definition Number of limited partnerships. + References No definition available. + Details
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Balance Type: | na
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X
- Definition Purchase of non controlling interests. + References No definition available. + Details
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Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Details
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