Subsequent Events/Other (Details) $ / shares in Units, $ in Thousands			1 Months Ended	3 Months Ended		9 Months Ended
	Oct. 14, 2016 USD ($) $ / shares	Mar. 10, 2016 USD ($) $ / shares	Oct. 28, 2016 USD ($)	Sep. 30, 2016 USD ($) $ / shares	Sep. 30, 2015 USD ($) $ / shares	Sep. 30, 2016 USD ($) property $ / shares	Sep. 30, 2015 USD ($) $ / shares
Other [Line Items]
Disposed Properties						92
Apartment Units						28,167
Sales Price						$ 6,699,958
Common Stock, Dividends, Per Share, Declared | $ / shares				$ 3.50375	$ 0.5525	$ 12.51125	$ 1.6575
Interest and other income				$ 5,509	$ 256	$ 65,092	$ 6,906
Litigation Settlement, Amount						2,900	5,800
Business Combination, Acquisition Related Costs						1,400	200
Noncash Project Abandonment Costs						3,379	2,322
Other Expenses						4,800	2,500
Real Estate [Member]
Other [Line Items]
Noncash Project Abandonment Costs						$ 3,400	2,300
Rental Properties – Consolidated
Other [Line Items]
Disposed Properties						91
Apartment Units						27,831
Sales Price						$ 6,568,003
Rental Properties – Consolidated | Subsequent Event [Member]
Other [Line Items]
Disposed Properties			1
Apartment Units			143
Sales Price			$ 29,000
Repayments Of Long-term Debt			300
Land [Member]
Other [Line Items]
Sales Price						$ 57,455
Military Housing [Member]
Other [Line Items]
Apartment Units						5,161
Sales Price						$ 63,300
Interest and other income						$ 52,400
Starwood Portfolio [Member]
Other [Line Items]
Disposed Properties | property						72
Apartment Units						23,262
Sales Price						$ 5,365,000
Common Stock, Dividends, Per Share, Declared | $ / shares		$ 8.00
Payments of Dividends		$ 3,000,000
Interest and other income				$ 10	$ 1	$ 21	$ 1
Starwood Portfolio [Member] | Subsequent Event [Member]
Other [Line Items]
Common Stock, Dividends, Per Share, Declared | $ / shares	$ 3.00
Payments of Dividends	$ 1,100,000
Starwood Portfolio [Member] | Rental Properties – Consolidated
Other [Line Items]
Disposed Properties | property						72
Apartment Units						23,262
Series P [Domain]
Other [Line Items]
Redemption of Series P Preference Units						$ 18,400
Reduction In Other Liabilities						$ 18,400
Series P [Domain]
Other [Line Items]
Preferred Stock Preference Units Dividend Rate Percentage						3.00%
Business Acquisition, Percentage of Voting Interests Acquired				95.00%		95.00%
2.85% Notes [Member] | Subsequent Event [Member]
Other [Line Items]
Proceeds from Issuance of Unsecured Debt			$ 500,000
Debt Instrument, Interest Rate, Stated Percentage			2.85%
Proceeds from Debt, Net of Issuance Costs			$ 496,700
Debt Instrument, Interest Rate, Effective Percentage			3.10%
Payments for (Proceeds from) Hedge, Investing Activities			$ 4,700