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Significant Accounting Policies (Details)		1 Months Ended	3 Months Ended								12 Months Ended
		Oct. 20, 2015	Dec. 31, 2015 USD ($)	Sep. 30, 2015 USD ($)	Jun. 30, 2015 USD ($)	Mar. 31, 2015 USD ($)	Dec. 31, 2014 USD ($) $ / shares	Sep. 30, 2014 USD ($) $ / shares	Jun. 30, 2014 USD ($) $ / shares	Mar. 31, 2014 USD ($) $ / shares	Dec. 31, 2015 USD ($) shares	Dec. 31, 2014 USD ($) shares	Dec. 31, 2013 USD ($) shares
Accounting Policies [Line Items]
Deferred Finance Costs, Net							$ 0					$ 0
Document Period End Date											Dec. 31, 2015
Significant Accounting Policies (Textual) [Abstract]
Development costs excluding direct costs and capitalized interest											$ 6,300,000	9,000,000	$ 11,100,000
Interest capitalized during period											16,100,000	20,200,000	29,400,000
Notes receivable			$ 16,694,000				14,369,000				16,694,000	14,369,000
Number of extension options on loan		2
Extension period of option on loan		6 months
Note maturity public capital threshold											5,000,000
Note receivable interest income											1,500,000	3,400,000	4,100,000
Deferred tax asset			11,762,000				6,976,000				11,762,000	6,976,000	32,273,000
Net of a valuation allowance			81,000				0				81,000	0	1,310,000
Valuation Allowance, Deferred Tax Asset, Change in Amount											100,000
Numerator for earnings per share — basic and diluted:
Net (loss)/income attributable to common stockholders			161,270,000	$ 12,361,000	$ 85,924,000	$ 72,891,000	$ 64,486,000	$ 39,618,000	$ 29,076,000	$ 17,430,000	$ 336,661,000	$ 150,610,000	$ 41,088,000
Weighted average common shares outstanding | shares											259,873,000	252,707,000	250,684,000
Net income/(loss) attributable to common stockholders — basic and diluted (in dollars per share) | $ / shares	[1]						$ 0.25	$ 0.16	$ 0.12	$ 0.07
Advertising expense											$ 6,400,000	$ 6,000,000	$ 5,700,000
Income Tax Expense (Benefit)											(3,886,000)	25,994,000	(8,281,000)
Income Tax Examination, Penalties and Interest Accrued			0								$ 0
Minimum Percentage of Carrying Value Of Real Estate Portfolio Held By Company											0.1
Interest Income, Related Party											$ 0.0	0.0	800,000
(Issuance)/repayment of notes receivable											(2,325,000)	68,664,000	$ (19,027,000)
Other Assets			137,302,000				$ 110,082,000				137,302,000	110,082,000
Secured debt, net			1,376,945,000				1,354,321,000				1,376,945,000	1,354,321,000
Unsecured debt, net			$ 2,193,850,000				2,210,978,000				$ 2,193,850,000	2,210,978,000
Note due February 2017
Significant Accounting Policies (Textual) [Abstract]
Notes receivable							11,869,000					11,869,000
Note Receivable Interest Rate			10.00%								10.00%
Aggregate Commitment on Note Receivable			$ 12,994,000								$ 12,994,000
Increase (Decrease) in Notes Receivables											1,100,000
Note maturity public capital threshold											5,000,000
Other
Significant Accounting Policies (Textual) [Abstract]
Notes receivable			$ 2,500,000				2,500,000				$ 2,500,000	2,500,000
Note Receivable Interest Rate			8.00%								8.00%
Note due October 2020 [Member]
Significant Accounting Policies (Textual) [Abstract]
Notes receivable			$ 1,200,000				0				$ 1,200,000	$ 0
Note Receivable Interest Rate			8.00%								8.00%
Aggregate Commitment on Note Receivable			$ 2,000,000								$ 2,000,000
Note maturity public capital threshold											$ 10,000,000
OP Units
Numerator for earnings per share — basic and diluted:
Antidilutive securities | shares											12,947,000	9,247,000	9,337,000
Preferred Stock
Numerator for earnings per share — basic and diluted:
Antidilutive securities | shares											3,032,000	3,036,000	3,036,000
Stock options and unvested restricted stock
Numerator for earnings per share — basic and diluted:
Antidilutive securities | shares											2,051,000	1,917,000	1,584,000
Minimum | Buildings
Significant Accounting Policies (Textual) [Abstract]
Estimated useful lives											35 years
Minimum | Building improvements
Significant Accounting Policies (Textual) [Abstract]
Estimated useful lives											10 years
Minimum | Furniture, fixtures, equipment, and other assets
Significant Accounting Policies (Textual) [Abstract]
Estimated useful lives											3 years
Maximum | Buildings
Significant Accounting Policies (Textual) [Abstract]
Estimated useful lives											55 years
Maximum | Building improvements
Significant Accounting Policies (Textual) [Abstract]
Estimated useful lives											35 years
Maximum | Furniture, fixtures, equipment, and other assets
Significant Accounting Policies (Textual) [Abstract]
Estimated useful lives											10 years
RedeemableNoncontrollingInterest [Member]
Accounting Policies [Line Items]
Other Comprehensive (Income) Loss, Net of Tax, Portion Attributable to Noncontrolling Interest											$ (308,000)	$ (133,000)	$ 250,000
Continuing Operations [Member]
Numerator for earnings per share — basic and diluted:
Income Tax Expense (Benefit)											(3,886,000)	(15,098,000)	(7,299,000)
Discontinued Operations [Member]
Numerator for earnings per share — basic and diluted:
Income Tax Expense (Benefit)											0	5,000	(982,000)
United Dominion Reality L P [Member]
Accounting Policies [Line Items]
Deferred Finance Costs, Net			2,199,000				4,500,000				$ 2,199,000	4,500,000
Document Period End Date											Dec. 31, 2015
Deferred Tax Liabilities, Net			0								$ 0
Significant Accounting Policies (Textual) [Abstract]
Development costs excluding direct costs and capitalized interest											700,000	2,000,000	2,500,000
Interest capitalized during period											200,000	2,900,000	5,900,000
Numerator for earnings per share — basic and diluted:
Advertising expense											$ 2,400,000	2,500,000	$ 2,500,000
Minimum Percentage of Carrying Value Of Real Estate Portfolio Held By Company											0.10
Other Assets			24,528,000				24,029,000				$ 24,528,000	24,029,000
Secured debt, net			475,964,000				927,484,000				$ 475,964,000	927,484,000
United Dominion Reality L P [Member] | Minimum | Buildings
Significant Accounting Policies (Textual) [Abstract]
Estimated useful lives											35 years
United Dominion Reality L P [Member] | Minimum | Building improvements
Significant Accounting Policies (Textual) [Abstract]
Estimated useful lives											10 years
United Dominion Reality L P [Member] | Minimum | Furniture, fixtures, equipment, and other assets
Significant Accounting Policies (Textual) [Abstract]
Estimated useful lives											3 years
United Dominion Reality L P [Member] | Maximum | Buildings
Significant Accounting Policies (Textual) [Abstract]
Estimated useful lives											55 years
United Dominion Reality L P [Member] | Maximum | Building improvements
Significant Accounting Policies (Textual) [Abstract]
Estimated useful lives											35 years
United Dominion Reality L P [Member] | Maximum | Furniture, fixtures, equipment, and other assets
Significant Accounting Policies (Textual) [Abstract]
Estimated useful lives											10 years
Preferred Stock
Numerator for earnings per share — basic and diluted:
Preferred stock, shares redeemed | shares											0
Reported Value Measurement [Member] | Fair Value, Measurements, Recurring [Member]
Significant Accounting Policies (Textual) [Abstract]
Notes receivable			16,694,000				14,369,000				$ 16,694,000	14,369,000
Secured Debt [Member]
Accounting Policies [Line Items]
Deferred Finance Costs, Net			5,549,000								5,549,000
Unsecured Debt [Member]
Accounting Policies [Line Items]
Deferred Finance Costs, Net			(12,400,000)								(12,400,000)
Reclassification of Deferred Financing Costs [Member]
Accounting Policies [Line Items]
Deferred Finance Costs, Net							22,686,000					22,686,000
Other Assets [Member]
Accounting Policies [Line Items]
Deferred Finance Costs, Net			(7,900,000)				(4,880,000)				(7,900,000)	(4,880,000)
Scenario, Previously Reported [Member]
Accounting Policies [Line Items]
Deferred Finance Costs, Net							(22,686,000)					(22,686,000)
Numerator for earnings per share — basic and diluted:
Other Assets							105,202,000					105,202,000
Secured debt, net							1,361,529,000					1,361,529,000
Unsecured debt, net							2,221,576,000					2,221,576,000
Scenario, Previously Reported [Member] | United Dominion Reality L P [Member]
Numerator for earnings per share — basic and diluted:
Secured debt, net							931,959,000					931,959,000
Secured Debt [Member]
Accounting Policies [Line Items]
Deferred Finance Costs, Net							7,208,000					7,208,000
Unsecured Debt [Member]
Accounting Policies [Line Items]
Deferred Finance Costs, Net			$ 12,373,000				$ 10,598,000				$ 12,373,000	$ 10,598,000
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