Commitments And Contingencies (Narrative) (Details) (USD $)	12 Months Ended
	Dec. 31, 2013 property	Dec. 31, 2012	Dec. 31, 2011	Nov. 30, 2012
Long-term Purchase Commitment [Line Items]
Ground leases, expiration date	Jun. 30, 2069
Operating leases, rental expense	$ 5,600,000	$ 5,700,000	$ 5,400,000
Number of real estate properties	2
Capital leases, total assets	16,800,000	16,800,000
Capital leases, accumulated depreciation	12,200,000	11,400,000
Capital leases, future minimum payments	30,216,000
Capital leases, future minimum payments, interest	9,200,000
Capital leases, future minimum payments, present value of net minimum payments	21,000,000
Shares issued in exchange of interests	0
Notes receivable from real estate joint ventures and partnerships	16,100,000			16,100,000
Receipt of cash and real property	19,100,000
Increase in noncontrolling interests	16,177,000	(394,000)	(1,668,000)
Total assets	4,223,929,000	4,184,784,000
Minimum [Member]
Long-term Purchase Commitment [Line Items]
Operating leases, term range, in years	1 year
Maximum [Member]
Long-term Purchase Commitment [Line Items]
Operating leases, term range, in years	25 years
DownREIT [Member]
Long-term Purchase Commitment [Line Items]
Number of real estate joint ventures	3	4
Shares issued in exchange of interests	0	0
Aggregate redemption value	41,000,000	42,000,000
Consoldiated Real Estate Joint Ventures [Member]
Long-term Purchase Commitment [Line Items]
Number of real estate joint ventures	2
Unconsolidated Real Estate Joint Ventures [Member]
Long-term Purchase Commitment [Line Items]
Number of real estate joint ventures	2
Total assets	1,283,166,000	1,519,447,000
Unconsolidated Real Estate Joint Ventures [Member] | Sheridan, Colorado [Member]
Long-term Purchase Commitment [Line Items]
Total assets	23,200,000
Capital Additions [Member]
Long-term Purchase Commitment [Line Items]
Construction contract, commitment	$ 66,000,000
Capital Additions [Member] | Minimum [Member]
Long-term Purchase Commitment [Line Items]
Construction contract, period (in months)	12
Capital Additions [Member] | Maximum [Member]
Long-term Purchase Commitment [Line Items]
Construction contract, period (in months)	36