Commitments and Contingencies (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013
Real Estate Properties [Line Items]
Costs Incurred to Date	$ 726,056
Expected Costs to Complete	391,903	[1]
Wholly owned — under development [Member]
Real Estate Properties [Line Items]
Number of properties	6
Costs Incurred to Date	433,707
Expected Costs to Complete	348,743
Average Ownership Stake	100.00%
Wholly owned — redevelopment [Member]
Real Estate Properties [Line Items]
Number of properties	2
Costs Incurred to Date	95,818
Expected Costs to Complete	39,482
Average Ownership Stake	100.00%
Unconsolidated joint ventures [Member]
Real Estate Properties [Line Items]
Number of properties	3
Costs Incurred to Date	196,531
Expected Costs to Complete	$ 3,678
Average Ownership Stake	76.00%

[1] Represents UDR's remaining equity commitment of unconsolidated joint ventures.