2.4.0.82204201 - Disclosure - Significant Accounting Policies (UNITED DOMINION REALTY, L.P.) (Policies)truefalsefalse1false falsefalseD2013Q2YTDhttp://www.sec.gov/CIK0000074208duration2013-01-01T00:00:002013-06-30T00:00:001true 3dei_EntityInformationLineItemsdei_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Entity Information [Line Items]2false 4us-gaap_NewAccountingPronouncementsPolicyPolicyTextBlockus-gaap_truenadurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1falsefalsefalse00<div style="font-family:Times New Roman;font-size:10pt;"><div style="line-height:120%;padding-top:13px;text-align:left;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;font-weight:bold;">Recent Accounting Pronouncements</font></div><div style="line-height:120%;padding-bottom:6px;padding-top:6px;text-align:left;text-indent:30px;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">In December 2011, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2011-10, </font><font style="font-family:inherit;font-size:10pt;font-style:italic;">Disclosures about Offsetting Assets and Liabilities. </font><font style="font-family:inherit;font-size:10pt;">The objective of this update is to provide enhanced disclosures that will enable users of its financial statements to evaluate the effect or potential effect of netting arrangements on an entity’s financial position. This includes the effect or potential effect of rights of setoff associated with an entity’s recognized assets and recognized liabilities within the scope of this update. The amendments require enhanced disclosures by requiring improved information about financial instruments and derivative instruments that are either 1) offset on the balance sheet in accordance with the “Offsetting Guidance” in ASC 210-20-45 or ASC 815-10-45 (collectively, the offsetting guidance) or 2) subject to an enforceable master netting arrangement or similar agreement, regardless of whether they are offset in accordance with the “Offsetting Guidance”. The amendments, which were adopted by the Company on January 1, 2013, impact the Company's disclosures related to its derivative activities. (See Note 10, </font><font style="font-family:inherit;font-size:10pt;font-style:italic;">Derivatives and Hedging Activity</font><font style="font-family:inherit;font-size:10pt;">.) The new guidance did not have any impact on the Company's consolidated financial position, results of operations, or cash flows.</font></div><div style="line-height:120%;text-align:left;text-indent:30px;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">In February 2012, the FASB issued ASU No. 2013-02</font><font style="font-family:inherit;font-size:10pt;font-style:italic;">, Other Comprehensive Income (Topic 220)</font><font style="font-family:inherit;font-size:10pt;"> to require preparers to report, in one place, information about reclassifications out of accumulated other comprehensive income. For significant items reclassified out of AOCI to net income in their entirety in the same reporting period, reporting (either on the face of the statement where net income is presented or in the notes thereto) is required about the effect of the reclassifications on the respective line items in the statement where net income is presented. For items that are not reclassified to net income in their entirety in the same reporting period, a cross reference to other existing disclosures is required in the notes. The amendments, which were adopted by the Company on January 1, 2013, did not have any impact on the Company's consolidated financial position, results of operations, or cash flows. The accompanying consolidated financial statements include the required disclosures in the Consolidated Statements of Comprehensive Income/(Loss) or in the notes thereto for each of the three and six month periods ended June 30, 2013 and 2012.</font></div></div>falsefalsefalsenonnum:textBlockItemTypenaDisclosure of the adoption of new accounting pronouncements that may impact the entity's financial reporting.No definition available.false0New Accounting Pronouncements, Policy [Policy Text Block]3false 4us-gaap_RevenueRecognitionRealEstateTransactionsPolicyus-gaap_truenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1falsefalsefalse00<div style="font-family:Times New Roman;font-size:10pt;"><div style="line-height:120%;padding-top:13px;text-align:left;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;font-weight:bold;">Revenue and real estate sales gain recognition</font></div><div style="line-height:120%;padding-top:13px;text-align:left;text-indent:32px;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">Rental income related to leases is recognized on an accrual basis when due from residents in accordance with GAAP. Rental payments are generally due on a monthly basis and recognized when earned. The Company recognizes interest income, management and other fees and incentives when earned, and the amounts are fixed and determinable.</font></div><div style="line-height:120%;padding-top:13px;text-align:left;text-indent:32px;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">The Company accounts for sales of real estate in accordance with GAAP. For sale transactions meeting the requirements for full accrual profit recognition, such as the Company no longer having continuing involvement in the property, we remove the related assets and liabilities from our Consolidated Balance Sheets and record the gain or loss in the period the transaction closes. For sale transactions that do not meet the full accrual sale criteria due to our continuing involvement, we evaluate the nature of the continuing involvement and account for the transaction under an alternate method of accounting. Unless certain limited criteria are met, non-monetary transactions, including property exchanges, are accounted for at fair value.</font></div><div style="line-height:120%;padding-top:13px;text-align:left;text-indent:32px;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">Sales to entities in which we retain or otherwise own an interest are accounted for as partial sales. If all other requirements for recognizing profit under the full accrual method have been satisfied and no other forms of continuing involvement are present, we recognize profit proportionate to the outside interest in the buyer and defer the gain on the interest we retain. The Company recognizes any deferred gain when the property is sold to a third party. In transactions accounted for by us as partial sales, we determine if the buyer of the majority equity interest in the venture was provided a preference as to cash flows in either an operating or a capital waterfall. If a cash flow preference has been provided, we recognize profit only to the extent that proceeds from the sale of the majority equity interest exceed costs related to the entire property.</font></div></div>falsefalsefalsenonnum:textBlockItemTypenaDisclosure of accounting policy for the timing and amount of revenue recognized on transfers of real estate, excluding retail land sales. The entity also may disclose its treatment of any unearned or deferred revenue that arises from the transaction.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=6367646&loc=d3e18780-107790 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 605 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SAB TOPIC 13.B.Q1) -URI http://asc.fasb.org/extlink&oid=6600647&loc=d3e214044-122780 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 360 -SubTopic 20 -Section 40 -Paragraph 7 -URI http://asc.fasb.org/extlink&oid=6854276&loc=d3e5041-110235 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 970 -SubTopic 605 -URI http://asc.fasb.org/subtopic&trid=2156320 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 360 -SubTopic 20 -Section 40 -Paragraph 28 -URI http://asc.fasb.org/extlink&oid=6854276&loc=d3e5304-110235 Reference 6: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 66 -Paragraph 6, 20 -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. false0Revenue and real estate sales gain recognition4false 4us-gaap_ComprehensiveIncomePolicyPolicyTextBlockus-gaap_truenadurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1falsefalsefalse00<div style="font-family:Times New Roman;font-size:10pt;"><div style="line-height:120%;padding-top:13px;text-align:left;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;font-weight:bold;">Comprehensive Income/(Loss)</font></div><div style="line-height:120%;padding-top:13px;text-align:left;text-indent:32px;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">Comprehensive income/(loss), which is defined as the change in equity during each period from transactions and other events and circumstances from nonowner sources, including all changes in equity during a period except for those resulting from investments by or distributions to stockholders, is displayed in the accompanying Consolidated Statements of Comprehensive Income/(Loss). For the </font><font style="font-family:inherit;font-size:10pt;color:#000000;text-decoration:none;">three and six months ended</font><font style="font-family:inherit;font-size:10pt;"> </font><font style="font-family:inherit;font-size:10pt;color:#000000;text-decoration:none;">June 30, 2013</font><font style="font-family:inherit;font-size:10pt;"> and </font><font style="font-family:inherit;font-size:10pt;color:#000000;text-decoration:none;">2012</font><font style="font-family:inherit;font-size:10pt;">, the Company's other comprehensive income/(loss) consisted of the gain/(loss) (effective portion) on derivative instruments that are designated as and qualify as cash flow hedges, loss reclassified from accumulated other comprehensive income/(loss) into earnings, and the allocation of other comprehensive income/(loss) to redeemable noncontrolling interests. The loss reclassified from accumulated other comprehensive income/(loss) is included in interest expense in the accompanying Consolidated Statements of Operations. See Note 10, </font><font style="font-family:inherit;font-size:10pt;font-style:italic;">Derivatives and Hedging Activity </font><font style="font-family:inherit;font-size:10pt;">for further discussion. The allocation of other comprehensive income/(loss) to redeemable noncontrolling interests during the three and six months ended </font><font style="font-family:inherit;font-size:10pt;color:#000000;text-decoration:none;">June 30, 2013</font><font style="font-family:inherit;font-size:10pt;"> and </font><font style="font-family:inherit;font-size:10pt;color:#000000;text-decoration:none;">2012</font><font style="font-family:inherit;font-size:10pt;"> was </font><font style="font-family:inherit;font-size:10pt;color:#000000;text-decoration:none;">$64,000</font><font style="font-family:inherit;font-size:10pt;"> and </font><font style="font-family:inherit;font-size:10pt;color:#000000;text-decoration:none;">$151,000</font><font style="font-family:inherit;font-size:10pt;"> and </font><font style="font-family:inherit;font-size:10pt;color:#000000;text-decoration:none;">$29,000</font><font style="font-family:inherit;font-size:10pt;"> and </font><font style="font-family:inherit;font-size:10pt;color:#000000;text-decoration:none;">$(38,000)</font><font style="font-family:inherit;font-size:10pt;">, respectively.</font></div></div>falsefalsefalsenonnum:textBlockItemTypenaDisclosure of accounting policy for comprehensive income.No definition available.false0Comprehensive Income, Policy [Policy Text Block]5false 4us-gaap_IncomeTaxPolicyTextBlockus-gaap_truenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1falsefalsefalse00<div style="font-family:Times New Roman;font-size:10pt;"><div style="line-height:120%;padding-top:13px;text-align:left;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;font-weight:bold;">Income Taxes</font></div><div style="line-height:120%;padding-top:13px;text-align:left;text-indent:32px;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">Due to the structure of the Company as a REIT and the nature of the operations for the operating properties, no provision for federal income taxes has been provided for at UDR. Historically, the Company has generally incurred only state and local excise and franchise taxes. UDR has elected for certain consolidated subsidiaries to be treated as Taxable REIT Subsidiaries (“TRS”), primarily those engaged in development activities.</font></div><div style="line-height:120%;padding-top:13px;text-align:left;text-indent:32px;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">Income taxes for our TRS are accounted for under the asset and liability method. Deferred tax assets and liabilities are recognized for future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax basis. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. The effect on deferred tax assets and liabilities from a change in tax rate is recognized in earnings in the period of the enactment date. The Company’s deferred tax assets are generally the result of differing depreciable lives on capitalized assets and the timing of expense recognition for certain accrued liabilities. As of </font><font style="font-family:inherit;font-size:10pt;color:#000000;text-decoration:none;">June 30, 2013</font><font style="font-family:inherit;font-size:10pt;">, UDR recorded a net income tax receivable of </font><font style="font-family:inherit;font-size:10pt;color:#000000;text-decoration:none;">$3.9 million</font><font style="font-family:inherit;font-size:10pt;"> and a deferred tax asset of </font><font style="font-family:inherit;font-size:10pt;color:#000000;text-decoration:none;">$25.3 million</font><font style="font-family:inherit;font-size:10pt;"> (net of a valuation allowance of </font><font style="font-family:inherit;font-size:10pt;color:#000000;text-decoration:none;">$1.4 million</font><font style="font-family:inherit;font-size:10pt;">), which are classified in "Other assets" on the Consolidated Balance Sheets. </font></div><div style="line-height:120%;text-align:left;text-indent:30px;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;"><br clear="none"/></font></div><div style="line-height:120%;text-align:left;text-indent:30px;font-size:11pt;"><font style="font-family:inherit;font-size:10pt;">Prior to 2012, RE</font><font style="font-family:inherit;font-size:10pt;"><sup style="vertical-align:top;line-height:120%;font-size:7pt">3</sup></font><font style="font-family:inherit;font-size:10pt;"> had a history of losses and, as a result, historically recognized a valuation allowance for net deferred tax assets.  Each quarter, the Company evaluates the need to retain all or a portion of the valuation allowance on its net deferred tax assets.  During the three months ended March 31, 2012, the Company determined that it was more likely than not that the deferred tax assets, including any remaining net operating loss carry forward, would be realized. In making this determination, the Company analyzed, among other things, its recent history of earnings from sales of depreciable property, forecasts of future earnings and its cumulative earnings for the last twelve quarters. The reversal of the valuation allowance in the first quarter of 2012 of </font><font style="font-family:inherit;font-size:10pt;color:#000000;text-decoration:none;">$22.9 million</font><font style="font-family:inherit;font-size:10pt;"> and the income tax benefit of </font><font style="font-family:inherit;font-size:10pt;color:#000000;text-decoration:none;">$2.8 million</font><font style="font-family:inherit;font-size:10pt;"> in the second quarter of 2012 resulted in an income tax benefit of </font><font style="font-family:inherit;font-size:10pt;color:#000000;text-decoration:none;">$25.7 million</font><font style="font-family:inherit;font-size:10pt;"> during the </font><font style="font-family:inherit;font-size:10pt;color:#000000;text-decoration:none;">six months ended</font><font style="font-family:inherit;font-size:10pt;"> </font><font style="font-family:inherit;font-size:10pt;color:#000000;text-decoration:none;">June 30, 2012</font><font style="font-family:inherit;font-size:10pt;">, which is reflected in continuing operations, and classified as "Tax benefit, net" in the Consolidated Statements of Operations. </font><font style="font-family:inherit;font-size:11pt;"> </font></div><div style="line-height:120%;padding-top:13px;text-align:left;text-indent:32px;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">GAAP defines a recognition threshold and measurement attribute for the financial statement recognition and measurement of a tax position taken or expected to be taken in a tax return. GAAP also provides guidance on derecognition, classification, interest and penalties, accounting for interim periods, disclosure and transition.</font></div><div style="line-height:120%;padding-top:13px;text-align:left;text-indent:32px;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">The Company recognizes its tax positions and evaluates them using a two-step process. First, UDR determines whether a tax position is more likely than </font><font style="font-family:inherit;font-size:10pt;color:#000000;text-decoration:none;">not (greater than 50 percent probability)</font><font style="font-family:inherit;font-size:10pt;"> to be sustained upon examination, including resolution of any related appeals or litigation processes, based on the technical merits of the position. The Company will then determine the amount of benefit to recognize and record the amount that is more likely than not to be realized upon ultimate settlement.</font></div><div style="line-height:120%;padding-top:13px;text-align:left;text-indent:32px;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">UDR had </font><font style="font-family:inherit;font-size:10pt;color:#000000;text-decoration:none;">no</font><font style="font-family:inherit;font-size:10pt;"> material unrecognized tax benefit, accrued interest or penalties at </font><font style="font-family:inherit;font-size:10pt;color:#000000;text-decoration:none;">June 30, 2013</font><font style="font-family:inherit;font-size:10pt;">. UDR and its subsidiaries are subject to federal income tax as well as income tax of various state jurisdictions. The tax years </font><font style="font-family:inherit;font-size:10pt;color:#000000;text-decoration:none;">2008 through 2011</font><font style="font-family:inherit;font-size:10pt;"> remain open to examination by tax jurisdictions to which we are subject. When applicable, UDR recognizes interest and/or penalties related to uncertain tax positions in income tax expense.</font></div></div>falsefalsefalsenonnum:textBlockItemTypenaDisclosure of accounting policy for income taxes, which may include its accounting policies for recognizing and measuring deferred tax assets and liabilities and related valuation allowances, recognizing investment tax credits, operating loss carryforwards, tax credit carryforwards, and other carryforwards, methodologies for determining its effective income tax rate and the characterization of interest and penalties in the financial statements.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Accounting Principles Board Opinion (APB) -Number 4 -Paragraph 11 -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. Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name FASB Interpretation (FIN) -Number 48 -Paragraph 20 -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. Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=6367646&loc=d3e18780-107790 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 45 -Paragraph 25 -URI http://asc.fasb.org/extlink&oid=21917399&loc=d3e32247-109318 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 19 -URI http://asc.fasb.org/extlink&oid=6907707&loc=d3e32840-109319 Reference 6: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 30 -URI http://asc.fasb.org/subtopic&trid=2144749 Reference 7: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 954 -SubTopic 740 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6491622&loc=d3e9504-115650 Reference 8: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -URI http://asc.fasb.org/subtopic&trid=2144681 Reference 9: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 17 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=6907707&loc=d3e32809-109319 Reference 10: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 45 -Paragraph 28 -URI http://asc.fasb.org/extlink&oid=21917399&loc=d3e32280-109318 Reference 11: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 109 -Paragraph 6-34, 43, 47, 49 -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. false0Income taxes6false 0truefalsetruefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse2false truefalseD2013Q2YTD_dei_LegalEntityAxis_udr_UnitedDominionRealityLPMemberhttp://www.sec.gov/CIK0000074208duration2013-01-01T00:00:002013-06-30T00:00:00falsefalseUnited Dominion Reality L.P. [Member]dei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldiudr_UnitedDominionRealityLPMemberdei_LegalEntityAxisexplicitMembernanafalse0United Dominion Reality L.P. [Member]7true 3dei_EntityInformationLineItemsdei_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Entity Information [Line Items]8false 4us-gaap_NewAccountingPronouncementsPolicyPolicyTextBlockus-gaap_truenadurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1falsefalsefalse00<div style="font-family:Times New Roman;font-size:10pt;"><div style="line-height:120%;padding-top:13px;text-align:left;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;font-weight:bold;">Recent Accounting Pronouncements</font></div><div style="line-height:120%;text-align:left;text-indent:30px;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;"><br clear="none"/></font></div><div style="line-height:120%;text-align:left;text-indent:30px;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">In December 2011, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2011-10, </font><font style="font-family:inherit;font-size:10pt;font-style:italic;">Disclosures about Offsetting Assets and Liabilities. </font><font style="font-family:inherit;font-size:10pt;">The objective of this update is to provide enhanced disclosures that will enable users of its financial statements to evaluate the effect or potential effect of netting arrangements on an entity’s financial position. This includes the effect or potential effect of rights of setoff associated with an entity’s recognized assets and recognized liabilities within the scope of this update. The amendments require enhanced disclosures by requiring improved information about financial instruments and derivative instruments that are either 1) offset on the balance sheet in accordance with the “Offsetting Guidance” in ASC 210-20-45 or ASC 815-10-45 (collectively, the offsetting guidance) or 2) subject to an enforceable master netting arrangement or similar agreement, regardless of whether they are offset in accordance with the “Offsetting Guidance”. The amendments, which were adopted by the Operating Partnership on January 1, 2013, impact the Operating Partnership's disclosures related to its derivative activities. (See Note 8, </font><font style="font-family:inherit;font-size:10pt;font-style:italic;">Derivatives and Hedging Activity</font><font style="font-family:inherit;font-size:10pt;">.) The new guidance did not have any impact on the Operating Partnership's consolidated financial position, results of operations, or cash flows.</font></div><div style="line-height:120%;text-align:left;text-indent:30px;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;"><br clear="none"/></font></div><div style="line-height:120%;text-align:left;text-indent:30px;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">In February 2012, the FASB issued ASU No. 2013-02</font><font style="font-family:inherit;font-size:10pt;font-style:italic;">, Other Comprehensive Income (Topic 220)</font><font style="font-family:inherit;font-size:10pt;"> to require preparers to report, in one place, information about reclassifications out of accumulated other comprehensive income. For significant items reclassified out of AOCI to net income in their entirety in the same reporting period, reporting (either on the face of the statement where net income is presented or in the notes thereto) is required about the effect of the reclassifications on the respective line items in the statement where net income is presented. For items that are not reclassified to net income in their entirety in the same reporting period, a cross reference to other existing disclosures is required in the notes. The amendments, which were adopted by the Operating Partnership on January 1, 2013, did not have any impact on the Operating Partnership's consolidated financial position, results of operations, or cash flows. The accompanying consolidated financial statements include the required disclosures in the Consolidated Statement of Comprehensive Income/(Loss) or in the notes thereto for each of the three and six month periods ended June 30, 2013 and 2012.</font></div></div>falsefalsefalsenonnum:textBlockItemTypenaDisclosure of the adoption of new accounting pronouncements that may impact the entity's financial reporting.No definition available.false0New Accounting Pronouncements, Policy [Policy Text Block]9false 4us-gaap_RevenueRecognitionRealEstateTransactionsPolicyus-gaap_truenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1falsefalsefalse00<div style="font-family:Times New Roman;font-size:10pt;"><div style="line-height:120%;padding-top:13px;text-align:left;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;font-weight:bold;">Revenue and Real Estate Sales Gain Recognition</font></div><div style="line-height:120%;padding-top:13px;text-align:left;text-indent:32px;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">Rental income related to leases is recognized on an accrual basis when due from residents in accordance with GAAP. Rental payments are generally due on a monthly basis and recognized when earned. The Operating Partnership recognizes interest income, management and other fees and incentives when earned, fixed and determinable.</font></div><div style="line-height:120%;padding-top:13px;text-align:left;text-indent:32px;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">The Operating Partnership accounts for sales of real estate in accordance with GAAP. For sale transactions meeting the requirements for full accrual profit recognition, such as the Operating Partnership no longer having continuing involvement in the property, we remove the related assets and liabilities from our Consolidated Balance Sheets and record the gain or loss in the period the transaction closes. For sale transactions that do not meet the full accrual sale criteria due to our continuing involvement, we evaluate the nature of the continuing involvement and account for the transaction under an alternate method of accounting. Unless certain limited criteria are met, non-monetary transactions, including property exchanges, are accounted for at fair value.</font></div><div style="line-height:120%;padding-top:13px;text-align:left;text-indent:32px;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">Sales to entities in which we or our General Partner retain or otherwise own an interest are accounted for as partial sales. If all other requirements for recognizing profit under the full accrual method have been satisfied and no other forms of continuing involvement are present, we recognize profit proportionate to the outside interest in the buyer and will defer the gain on the interest we or our General Partner retain. The Operating Partnership will recognize any deferred gain when the property is then sold to a third party. In transactions accounted by us as partial sales, we determine if the buyer of the majority equity interest in the venture was provided a preference as to cash flows in either an operating or a capital waterfall. If a cash flow preference has been provided, we recognize profit only to the extent that proceeds from the sale of the majority equity interest exceed costs related to the entire property.</font></div></div>falsefalsefalsenonnum:textBlockItemTypenaDisclosure of accounting policy for the timing and amount of revenue recognized on transfers of real estate, excluding retail land sales. The entity also may disclose its treatment of any unearned or deferred revenue that arises from the transaction.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=6367646&loc=d3e18780-107790 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 605 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SAB TOPIC 13.B.Q1) -URI http://asc.fasb.org/extlink&oid=6600647&loc=d3e214044-122780 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 360 -SubTopic 20 -Section 40 -Paragraph 7 -URI http://asc.fasb.org/extlink&oid=6854276&loc=d3e5041-110235 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 970 -SubTopic 605 -URI http://asc.fasb.org/subtopic&trid=2156320 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 360 -SubTopic 20 -Section 40 -Paragraph 28 -URI http://asc.fasb.org/extlink&oid=6854276&loc=d3e5304-110235 Reference 6: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 66 -Paragraph 6, 20 -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. false0Revenue and real estate sales gain recognition10false 4us-gaap_ComprehensiveIncomePolicyPolicyTextBlockus-gaap_truenadurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1falsefalsefalse00<div style="font-family:Times New Roman;font-size:10pt;"><div style="line-height:120%;padding-top:13px;text-align:left;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;font-weight:bold;">Comprehensive Income/(Loss)</font></div><div style="line-height:120%;padding-top:13px;text-align:left;text-indent:32px;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">Comprehensive income/(loss), which is defined as the change in equity during each period from transactions and other events and circumstances from nonowner sources, including all changes in equity during a period except for those resulting from investments by or distributions to stockholders, is displayed in the accompanying Consolidated Statements of Comprehensive Income/(Loss). For the three and six months ended </font><font style="font-family:inherit;font-size:10pt;color:#000000;text-decoration:none;">June 30, 2013</font><font style="font-family:inherit;font-size:10pt;"> and </font><font style="font-family:inherit;font-size:10pt;color:#000000;text-decoration:none;">2012</font><font style="font-family:inherit;font-size:10pt;">, the Operating Partnership's other comprehensive income/(loss) consisted of the loss (effective portion) on derivative instruments that are designated as and qualify as cash flow hedges and loss reclassified from accumulated other comprehensive income/(loss) into earnings. The loss reclassified from accumulated other comprehensive income/(loss) is included in interest expense in the accompanying Consolidated Statements of Operations. See Note 8, </font><font style="font-family:inherit;font-size:10pt;font-style:italic;">Derivatives and Hedging Activity </font><font style="font-family:inherit;font-size:10pt;">for further discussion. </font></div></div>falsefalsefalsenonnum:textBlockItemTypenaDisclosure of accounting policy for comprehensive income.No definition available.false0Comprehensive Income, Policy [Policy Text Block]11false 4us-gaap_IncomeTaxPolicyTextBlockus-gaap_truenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1falsefalsefalse00<div style="font-family:Times New Roman;font-size:10pt;"><div style="line-height:120%;padding-top:13px;text-align:left;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;font-weight:bold;">Income taxes</font></div><div style="line-height:120%;padding-top:13px;text-align:left;text-indent:32px;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">The taxable income or loss of the Operating Partnership is reported on the tax returns of the partners. Accordingly, no provision has been made in the accompanying financial statements for federal or state income taxes on income that is passed through to the partners. However, any state or local revenue, excise or franchise taxes that result from the operating activities of the Operating Partnership are recorded at the entity level. The Operating Partnership’s tax returns are subject to examination by federal and state taxing authorities. Net income for financial reporting purposes differs from the net income for income tax reporting purposes primarily due to temporary differences, principally real estate depreciation and the tax deferral of certain gains on property sales. The differences in depreciation result from differences in the book and tax basis of certain real estate assets and the differences in the methods of depreciation and lives of the real estate assets.</font></div><div style="line-height:120%;padding-top:13px;text-align:left;text-indent:32px;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">The Operating Partnership evaluates the accounting and disclosure of tax positions taken or expected to be taken in the course of preparing the Operating Partnership’s tax returns to determine whether the tax positions are “more-likely-than-not” of being sustained by the applicable tax authority. Tax positions not deemed to meet the more-likely-than-not threshold would be recorded as a tax benefit or expense in the current year. Management of the Operating Partnership is required to analyze all open tax years, as defined by the statute of limitations, for all major jurisdictions, which include federal and certain states. The Operating Partnership has no examinations in progress and none are expected at this time.</font></div><div style="line-height:120%;padding-top:13px;text-align:left;text-indent:32px;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">Management of the General Partner has reviewed all open tax years (</font><font style="font-family:inherit;font-size:10pt;color:#000000;text-decoration:none;">2009 through 2011</font><font style="font-family:inherit;font-size:10pt;">) of tax jurisdictions and concluded there is no material tax liability resulting from unrecognized tax benefits relating to uncertain income tax positions taken or expected to be taken in future tax returns.</font></div></div>falsefalsefalsenonnum:textBlockItemTypenaDisclosure of accounting policy for income taxes, which may include its accounting policies for recognizing and measuring deferred tax assets and liabilities and related valuation allowances, recognizing investment tax credits, operating loss carryforwards, tax credit carryforwards, and other carryforwards, methodologies for determining its effective income tax rate and the characterization of interest and penalties in the financial statements.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Accounting Principles Board Opinion (APB) -Number 4 -Paragraph 11 -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. Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name FASB Interpretation (FIN) -Number 48 -Paragraph 20 -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. Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=6367646&loc=d3e18780-107790 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 45 -Paragraph 25 -URI http://asc.fasb.org/extlink&oid=21917399&loc=d3e32247-109318 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 19 -URI http://asc.fasb.org/extlink&oid=6907707&loc=d3e32840-109319 Reference 6: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 30 -URI http://asc.fasb.org/subtopic&trid=2144749 Reference 7: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 954 -SubTopic 740 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6491622&loc=d3e9504-115650 Reference 8: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -URI http://asc.fasb.org/subtopic&trid=2144681 Reference 9: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 17 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=6907707&loc=d3e32809-109319 Reference 10: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 45 -Paragraph 28 -URI http://asc.fasb.org/extlink&oid=21917399&loc=d3e32280-109318 Reference 11: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 109 -Paragraph 6-34, 43, 47, 49 -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. false0Income taxes12false 4us-gaap_EarningsPerSharePolicyTextBlockus-gaap_truenadurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1falsefalsefalse00<div style="font-family:Times New Roman;font-size:10pt;"><div style="line-height:120%;padding-top:13px;text-align:left;text-indent:32px;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">.</font></div></div><div style="font-family:Times New Roman;font-size:10pt;"><div style="line-height:120%;padding-top:13px;text-align:left;text-indent:32px;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">Basic earnings per OP Unit is computed by dividing net income/(loss) attributable to general and limited partner units by the weighted average number of general and limited partner units (including redeemable OP Units) outstanding during the year. Diluted earnings per OP Unit reflects the potential dilution that could occur if securities or other contracts to issue OP Units were exercised or converted into OP Units or resulted in the issuance of OP Units that shared in the earnings of the Operating Partnership. For the </font><font style="font-family:inherit;font-size:10pt;color:#000000;text-decoration:none;">three and six months ended June 30, 2013 and 2012</font><font style="font-family:inherit;font-size:10pt;">, there were </font><font style="font-family:inherit;font-size:10pt;color:#000000;text-decoration:none;">no</font><font style="font-family:inherit;font-size:10pt;"> dilutive instruments outstanding, and therefore, diluted earnings per OP Unit and basic earnings per OP Unit are the same.</font></div></div>falsefalsefalsenonnum:textBlockItemTypenaDisclosure of accounting policy for computing basic and diluted earnings or loss per share for each class of common stock and participating security. Addresses all significant policy factors, including any antidilutive items that have been excluded from the computation and takes into account stock dividends, splits and reverse splits that occur after the balance sheet date of the latest reporting period but before the issuance of the financial statements.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=6367646&loc=d3e18780-107790 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 260 -SubTopic 10 -Section 50 -Paragraph 1 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=6371337&loc=d3e3550-109257 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 260 -SubTopic 10 -URI http://asc.fasb.org/subtopic&trid=2144384 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 128 -Paragraph 40 -Subparagraph a -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. Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 260 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6371337&loc=d3e3630-109257 Reference 6: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 128 -Paragraph 6, 8-16, 60 -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. false0Earnings per OP unitfalseSignificant Accounting Policies (UNITED DOMINION REALTY, L.P.) (Policies)UnKnownUnKnownUnKnownUnKnowntruefalsefalseSheethttp://www.udr.com/role/SignificantAccountingPoliciesUnitedDominionRealtyLPPolicies112