Segment Information (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Financial data of reportable segments
Total Assets	$ 9,960,241,000		$ 9,960,241,000		$ 8,814,940,000
Operating Expenses	173,209,000	$ 150,154,000	500,692,000	$ 467,064,000
Revenues	289,057,000	234,743,000	785,898,000	713,917,000
Depreciation and amortization	79,966,000	55,511,000	206,782,000	169,838,000
Interest and other income	8,995,000	10,096,000	27,977,000	33,974,000
Interest expense	49,007,000	59,312,000	149,335,000	178,917,000
Capital expenditures	146,538,000	83,360,000	338,490,000	295,182,000
Commercial Group [Member]
Financial data of reportable segments
Total Assets	5,015,253,000		5,015,253,000		4,210,714,000
Operating Expenses	79,720,000	70,224,000	226,929,000	224,929,000
Revenues	159,706,000	129,345,000	422,858,000	383,221,000
Depreciation and amortization	48,819,000	29,304,000	115,392,000	91,756,000
Interest and other income	1,708,000	1,579,000	5,614,000	5,585,000
Interest expense	29,040,000	31,093,000	89,211,000	97,938,000
Capital expenditures	50,788,000	17,655,000	122,001,000	98,033,000
Residential Group [Member]
Financial data of reportable segments
Total Assets	3,583,466,000		3,583,466,000		3,172,188,000
Operating Expenses	44,715,000	43,704,000	134,117,000	127,046,000
Revenues	79,703,000	63,303,000	230,223,000	190,525,000
Depreciation and amortization	21,670,000	16,608,000	62,363,000	49,660,000
Interest and other income	3,030,000	5,101,000	9,790,000	18,145,000
Interest expense	6,019,000	8,030,000	12,629,000	23,032,000
Capital expenditures	83,250,000	62,795,000	199,433,000	187,656,000
Arena [Member]
Financial data of reportable segments
Total Assets	955,409,000		955,409,000		955,570,000
Operating Expenses	17,199,000	17,105,000	55,019,000	55,399,000
Revenues	24,637,000	25,039,000	80,497,000	84,968,000
Depreciation and amortization	8,811,000	8,793,000	26,403,000	25,999,000
Interest and other income	0	0	0	0
Interest expense	9,415,000	10,895,000	29,650,000	30,101,000
Capital expenditures	12,500,000	2,890,000	17,022,000	9,442,000
Land Development Group [Member]
Financial data of reportable segments
Total Assets	275,502,000		275,502,000		250,833,000
Operating Expenses	11,869,000	5,358,000	23,234,000	24,307,000
Revenues	25,011,000	17,056,000	52,320,000	55,203,000
Depreciation and amortization	28,000	88,000	540,000	269,000
Interest and other income	4,213,000	3,384,000	12,394,000	10,091,000
Interest expense	(189,000)	(287,000)	(1,059,000)	(572,000)
Capital expenditures	0	20,000	15,000	36,000
Corporate Activities [Member]
Financial data of reportable segments
Total Assets	130,611,000		130,611,000		$ 225,635,000
Operating Expenses	19,706,000	13,763,000	61,393,000	35,383,000
Revenues	0	0	0	0
Depreciation and amortization	638,000	718,000	2,084,000	2,154,000
Interest and other income	44,000	32,000	179,000	153,000
Interest expense	4,722,000	9,581,000	18,904,000	28,418,000
Capital expenditures	$ 0	$ 0	$ 19,000	$ 15,000