Accounting Policies Accounting Policies (Details 3) (USD $)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Investing Activities
Increase in projects under construction and development	$ (12,577,000)	$ (9,345,000)
(Increase) decrease in completed rental properties	(33,486,000)	53,285,000
Increase in restricted cash	0	(387,000)
Increase in investments in and advances to affiliates	(12,921,000)	(9,158,000)
Total effect on investing activities	(58,984,000)	34,395,000
Financing Activities
Increase (decrease) in nonrecourse mortgage debt and notes payable	36,276,000	(33,812,000)
Decrease in convertible senior debt	(286,196,000)	0
Increase in Class A common stock	4,548,000	0
Increase (decrease) in additional paid-in capital	285,391,000	(26,473,000)
Increase in treasury stock	(6,503,000)	0
Increase in redeemable noncontrolling interest	0	28,390,000
(Decrease) increase in noncontrolling interest	(532,000)	4,000
Total effect on financing activities	$ 32,984,000	$ (31,891,000)