Fair Value (Details) (USD $)	3 Months Ended
	Mar. 31, 2013 derivative	Mar. 31, 2012
Derivative instruments and Hedging Activities
Amount of forward interest rate protection agreement	$ 215,000,000
Charge for the reversal of the deferred loss	53,484,000
Archstone Enterprise LP
Derivative instruments and Hedging Activities
Number of derivative instruments held	10
Fair value	20,000
Puts
Derivative instruments and Hedging Activities
Number of derivative instruments held	2
Cash Flow Hedges
Derivative instruments and Hedging Activities
Number of derivative instruments held	4
Amount of increase in comprehensive income to adjust hedging derivatives		11,008,000
Hedging losses reclassified from accumulated other comprehensive loss into earnings	1,391,000
Estimated hedging losses to be reclassified from accumulated other comprehensive loss into earnings within the next twelve months	5,493,000
Cash Flow Hedges | Interest Rate Caps
Derivative instruments and Hedging Activities
Notional balance	179,675
Weighted average interest rate (as a percent)	2.40%
Weighted average capped interest rate (as a percent)	5.30%
Cash Flow Hedges | Interest Rate Swaps
Derivative instruments and Hedging Activities
Notional balance	215,000
Weighted average interest rate (as a percent)	4.60%
Non-Designated Hedges
Derivative instruments and Hedging Activities
Number of derivative instruments held	14
Unrecognized gain, included in interest expense	1,414,000
Non-Designated Hedges | Interest Rate Caps
Derivative instruments and Hedging Activities
Notional balance	$ 568,514
Weighted average interest rate (as a percent)	1.50%
Weighted average capped interest rate (as a percent)	5.80%