<?xml version="1.0" encoding="us-ascii"?><InstanceReport xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"><Version>2.4.0.8</Version><ReportLongName>2110100 - Disclosure - Noncontrolling Interests</ReportLongName><DisplayLabelColumn>true</DisplayLabelColumn><ShowElementNames>false</ShowElementNames><RoundingOption /><HasEmbeddedReports>false</HasEmbeddedReports><Columns><Column FlagID="0"><Id>1</Id><IsAbstractGroupTitle>false</IsAbstractGroupTitle><LabelSeparator>

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</LabelSeparator><Level>1</Level><ElementName>us-gaap_MinorityInterestAbstract</ElementName><ElementPrefix>us-gaap_</ElementPrefix><IsBaseElement>true</IsBaseElement><BalanceType>na</BalanceType><PeriodType>duration</PeriodType><IsReportTitle>false</IsReportTitle><IsSegmentTitle>false</IsSegmentTitle><IsCalendarTitle>false</IsCalendarTitle><IsEquityPrevioslyReportedAsRow>false</IsEquityPrevioslyReportedAsRow><IsEquityAdjustmentRow>false</IsEquityAdjustmentRow><IsBeginningBalance>false</IsBeginningBalance><IsEndingBalance>false</IsEndingBalance><IsReverseSign>false</IsReverseSign><FootnoteIndexer /><Cells><Cell FlagID="0" ContextID="" UnitID=""><Id>1</Id><IsNumeric>false</IsNumeric><IsRatio>false</IsRatio><DisplayZeroAsNone>false</DisplayZeroAsNone><NumericAmount>0</NumericAmount><RoundedNumericAmount>0</RoundedNumericAmount><NonNumbericText /><FootnoteIndexer /><CurrencyCode /><CurrencySymbol /><IsIndependantCurrency>false</IsIndependantCurrency><ShowCurrencySymbol>false</ShowCurrencySymbol><DisplayDateInUSFormat>false</DisplayDateInUSFormat></Cell></Cells><ElementDataType>xbrli:stringItemType</ElementDataType><SimpleDataType>string</SimpleDataType><IsTotalLabel>false</IsTotalLabel><UnitID>0</UnitID><Label>Stockholders' Equity Attributable to Noncontrolling Interest [Abstract]</Label></Row><Row FlagID="0"><Id>2</Id><IsAbstractGroupTitle>false</IsAbstractGroupTitle><LabelSeparator>

</LabelSeparator><Level>2</Level><ElementName>us-gaap_MinorityInterestDisclosureTextBlock</ElementName><ElementPrefix>us-gaap_</ElementPrefix><IsBaseElement>true</IsBaseElement><BalanceType>na</BalanceType><PeriodType>duration</PeriodType><IsReportTitle>false</IsReportTitle><IsSegmentTitle>false</IsSegmentTitle><IsCalendarTitle>false</IsCalendarTitle><IsEquityPrevioslyReportedAsRow>false</IsEquityPrevioslyReportedAsRow><IsEquityAdjustmentRow>false</IsEquityAdjustmentRow><IsBeginningBalance>false</IsBeginningBalance><IsEndingBalance>false</IsEndingBalance><IsReverseSign>false</IsReverseSign><PreferredLabelRole>verboseLabel</PreferredLabelRole><FootnoteIndexer /><Cells><Cell FlagID="0" ContextID="D2013Q2YTD" UnitID=""><Id>1</Id><IsNumeric>false</IsNumeric><IsRatio>false</IsRatio><DisplayZeroAsNone>false</DisplayZeroAsNone><NumericAmount>0</NumericAmount><RoundedNumericAmount>0</RoundedNumericAmount><NonNumbericText>&lt;div style="font-family:Times New Roman;font-size:10pt;"&gt;&lt;div style="line-height:120%;padding-top:12px;font-size:10pt;"&gt;&lt;font style="font-family:inherit;font-size:10pt;font-weight:bold;text-decoration:underline;"&gt;Noncontrolling Interests of the Trust&lt;/font&gt;&lt;/div&gt;&lt;div style="line-height:120%;padding-top:6px;text-align:justify;font-size:10pt;"&gt;&lt;font style="font-family:inherit;font-size:10pt;"&gt;Noncontrolling interests in the accompanying financial statements represent the interests of the common and preferred units in the Operating Partnership not held by the Trust. In addition, noncontrolling interests include third-party ownership interests in consolidated joint venture investments.&lt;/font&gt;&lt;/div&gt;&lt;div style="line-height:120%;padding-top:18px;font-size:10pt;"&gt;&lt;font style="font-family:inherit;font-size:10pt;font-weight:bold;"&gt;Common units&lt;/font&gt;&lt;/div&gt;&lt;div style="line-height:120%;padding-top:6px;text-align:justify;font-size:10pt;"&gt;&lt;font style="font-family:inherit;font-size:10pt;"&gt;The common units outstanding of the Operating Partnership not held by the Trust as of &lt;/font&gt;&lt;font style="font-family:inherit;font-size:10pt;color:#000000;text-decoration:none;"&gt;June&amp;#160;30, 2013&lt;/font&gt;&lt;font style="font-family:inherit;font-size:10pt;"&gt; have the same economic characteristics as common shares of the Trust. The &lt;/font&gt;&lt;font style="font-family:inherit;font-size:10pt;color:#000000;text-decoration:none;"&gt;3,713,851&lt;/font&gt;&lt;font style="font-family:inherit;font-size:10pt;"&gt; outstanding common units of the Operating Partnership at such date not held by the Trust share proportionately in the net income or loss and in any distributions of the Operating Partnership. The common units of the Operating Partnership not held by the Trust are redeemable at any time at the option of the holder. The Trust, as the sole general partner of the Operating Partnership, may at its option elect to settle the redemption in cash or through the exchange on a one-for-one basis with unregistered common shares of the Trust. The market value of the &lt;/font&gt;&lt;font style="font-family:inherit;font-size:10pt;color:#000000;text-decoration:none;"&gt;3,713,851&lt;/font&gt;&lt;font style="font-family:inherit;font-size:10pt;"&gt; outstanding common units based on the closing price of the common shares of the Trust at &lt;/font&gt;&lt;font style="font-family:inherit;font-size:10pt;color:#000000;text-decoration:none;"&gt;June&amp;#160;30, 2013&lt;/font&gt;&lt;font style="font-family:inherit;font-size:10pt;"&gt; was $&lt;/font&gt;&lt;font style="font-family:inherit;font-size:10pt;color:#000000;text-decoration:none;"&gt;137.3 million&lt;/font&gt;&lt;font style="font-family:inherit;font-size:10pt;"&gt;.&lt;/font&gt;&lt;/div&gt;&lt;div style="line-height:120%;padding-top:18px;font-size:10pt;"&gt;&lt;font style="font-family:inherit;font-size:10pt;font-weight:bold;"&gt;Preferred units&lt;/font&gt;&lt;/div&gt;&lt;div style="line-height:120%;padding-top:6px;text-align:justify;font-size:10pt;"&gt;&lt;font style="font-family:inherit;font-size:10pt;"&gt;The Trust had no outstanding cumulative redeemable preferred units of the Operating Partnership (the &amp;#8220;Equity Preferred Units&amp;#8221;) as of &lt;/font&gt;&lt;font style="font-family:Times New Roman;font-size:10pt;color:#000000;font-style:normal;font-weight:normal;text-decoration:none;"&gt;June&amp;#160;30, 2013&lt;/font&gt;&lt;font style="font-family:inherit;font-size:10pt;"&gt;. During the three months ended &lt;/font&gt;&lt;font style="font-family:inherit;font-size:10pt;color:#000000;text-decoration:none;"&gt;June&amp;#160;30, 2013&lt;/font&gt;&lt;font style="font-family:inherit;font-size:10pt;"&gt;, the Company redeemed &lt;/font&gt;&lt;font style="font-family:inherit;font-size:10pt;color:#000000;text-decoration:none;"&gt;$20.0 million&lt;/font&gt;&lt;font style="font-family:inherit;font-size:10pt;"&gt; of outstanding &lt;/font&gt;&lt;font style="font-family:inherit;font-size:10pt;color:#000000;text-decoration:none;"&gt;7.00%&lt;/font&gt;&lt;font style="font-family:inherit;font-size:10pt;"&gt; Series E Cumulative Redeemable Preferred Units, &lt;/font&gt;&lt;font style="font-family:inherit;font-size:10pt;color:#000000;text-decoration:none;"&gt;$17.5 million&lt;/font&gt;&lt;font style="font-family:inherit;font-size:10pt;"&gt; of outstanding &lt;/font&gt;&lt;font style="font-family:inherit;font-size:10pt;color:#000000;text-decoration:none;"&gt;6.65%&lt;/font&gt;&lt;font style="font-family:inherit;font-size:10pt;"&gt; Series F Cumulative Redeemable Preferred Units and &lt;/font&gt;&lt;font style="font-family:inherit;font-size:10pt;color:#000000;text-decoration:none;"&gt;$27.0 million&lt;/font&gt;&lt;font style="font-family:inherit;font-size:10pt;"&gt; of outstanding &lt;/font&gt;&lt;font style="font-family:inherit;font-size:10pt;color:#000000;text-decoration:none;"&gt;6.70%&lt;/font&gt;&lt;font style="font-family:inherit;font-size:10pt;"&gt; Series G Cumulative Redeemable Preferred Units, all at par. In connection with these redemptions, the Company wrote off &lt;/font&gt;&lt;font style="font-family:inherit;font-size:10pt;color:#000000;text-decoration:none;"&gt;$1.2 million&lt;/font&gt;&lt;font style="font-family:inherit;font-size:10pt;"&gt; in origination costs. These amounts are included in noncontrolling interest - operating partnership in the Trust's consolidated statements of comprehensive income.&lt;/font&gt;&lt;/div&gt;&lt;/div&gt;</NonNumbericText><FootnoteIndexer /><CurrencyCode /><CurrencySymbol /><IsIndependantCurrency>false</IsIndependantCurrency><ShowCurrencySymbol>false</ShowCurrencySymbol><DisplayDateInUSFormat>false</DisplayDateInUSFormat></Cell></Cells><ElementDataType>nonnum:textBlockItemType</ElementDataType><SimpleDataType>na</SimpleDataType><ElementDefenition>The entire disclosure for noncontrolling interest in consolidated subsidiaries, which could include the name of the subsidiary, the ownership percentage held by the parent, the ownership percentage held by the noncontrolling owners, the amount of the noncontrolling interest, the location of this amount on the balance sheet (when not reported separately), an explanation of the increase or decrease in the amount of the noncontrolling interest, the noncontrolling interest share of the net Income or Loss of the subsidiary, the location of this amount on the income statement (when not reported separately), the nature of the noncontrolling interest such as background information and terms, the amount of the noncontrolling interest represented by preferred stock, a description of the preferred stock, and the dividend requirements of the preferred stock.</ElementDefenition><ElementReferences>Reference 1: http://www.xbrl.org/2003/role/presentationRef

 -Publisher FASB

 -Name Accounting Standards Codification

 -Topic 210

 -SubTopic 10

 -Section S99

 -Paragraph 1

 -Subparagraph (SX 210.5-02.31)

 -URI http://asc.fasb.org/extlink&amp;oid=6877327&amp;loc=d3e13212-122682



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

 -Publisher FASB

 -Name Accounting Standards Codification

 -Topic 810

 -SubTopic 10

 -Section 50

 -Paragraph 1A

 -URI http://asc.fasb.org/extlink&amp;oid=18733093&amp;loc=SL4573702-111684



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

 -Publisher AICPA

 -Name Accounting Research Bulletin (ARB)

 -Number 51

 -Paragraph 38

 -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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