Segment Information (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Financial data of reportable segments
Total Assets	$ 10,328,303,000		$ 10,328,303,000		$ 8,814,940,000
Operating Expenses	166,840,000	$ 145,807,000	327,483,000	$ 316,910,000
Operating Expenses			327,483,000	316,910,000
Revenues			496,841,000	479,174,000
Revenues	259,759,000	229,637,000	496,841,000	479,174,000
Depreciation and amortization	65,002,000	59,318,000	126,816,000	114,327,000
Interest and other income	9,278,000	12,375,000	18,982,000	23,878,000
Interest expense	47,752,000	57,153,000	100,328,000	119,605,000
Capital expenditures	116,963,000	121,069,000	191,952,000	211,822,000
Commercial Group [Member]
Financial data of reportable segments
Total Assets	5,513,274,000		5,513,274,000		4,210,714,000
Operating Expenses	74,119,000	73,157,000
Operating Expenses			147,209,000	154,705,000
Revenues			263,152,000	253,876,000
Revenues	134,607,000	123,791,000
Depreciation and amortization	33,722,000	32,193,000	66,573,000	62,452,000
Interest and other income	1,273,000	2,222,000	3,906,000	4,006,000
Interest expense	29,849,000	32,279,000	60,171,000	66,845,000
Capital expenditures	42,331,000	49,381,000	71,213,000	80,378,000
Residential Group [Member]
Financial data of reportable segments
Total Assets	3,463,997,000		3,463,997,000		3,172,188,000
Operating Expenses	46,163,000	37,673,000
Operating Expenses			89,402,000	83,342,000
Revenues			150,520,000	127,222,000
Revenues	80,860,000	61,553,000
Depreciation and amortization	21,317,000	17,656,000	40,693,000	33,052,000
Interest and other income	3,764,000	6,599,000	6,760,000	13,044,000
Interest expense	2,145,000	5,817,000	6,610,000	15,002,000
Capital expenditures	72,743,000	71,058,000	116,183,000	124,861,000
Arena [Member]
Financial data of reportable segments
Total Assets	960,302,000		960,302,000		955,570,000
Operating Expenses	17,862,000	14,818,000
Operating Expenses			37,820,000	38,294,000
Revenues			55,860,000	59,929,000
Revenues	27,040,000	24,572,000
Depreciation and amortization	8,802,000	8,674,000	17,592,000	17,206,000
Interest and other income	0	0	0	0
Interest expense	10,127,000	9,649,000	20,235,000	19,206,000
Capital expenditures	1,870,000	615,000	4,522,000	6,552,000
Land Development Group [Member]
Financial data of reportable segments
Total Assets	261,910,000		261,910,000		250,833,000
Operating Expenses	6,724,000	10,100,000
Operating Expenses			11,365,000	18,949,000
Revenues			27,309,000	38,147,000
Revenues	17,252,000	19,721,000
Depreciation and amortization	423,000	95,000	512,000	181,000
Interest and other income	4,141,000	3,462,000	8,181,000	6,707,000
Interest expense	(405,000)	(147,000)	(870,000)	(285,000)
Capital expenditures	0	0	15,000	16,000
Corporate Activities [Member]
Financial data of reportable segments
Total Assets	128,820,000		128,820,000		$ 225,635,000
Operating Expenses	21,972,000	10,059,000
Operating Expenses			41,687,000	21,620,000
Revenues			0	0
Revenues	0	0
Depreciation and amortization	738,000	700,000	1,446,000	1,436,000
Interest and other income	100,000	92,000	135,000	121,000
Interest expense	6,036,000	9,555,000	14,182,000	18,837,000
Capital expenditures	$ 19,000	$ 15,000	$ 19,000	$ 15,000