Segment Reporting (Schedule of Segments) (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016 USD ($)	Jun. 30, 2015 USD ($)	Jun. 30, 2016 USD ($) segments	Jun. 30, 2015 USD ($)	Dec. 31, 2015 USD ($)
Segment Reporting
Number of reportable segments | segments			4
Operating lease income	$ 54,518	$ 56,152	$ 109,455	$ 115,291
Interest income	34,400	33,729	67,620	68,625
Other income	10,097	12,761	21,637	23,325
Land development revenue	27,888	6,543	42,835	14,801
Earnings (loss) from equity method investments	39,447	8,785	47,714	15,332
Income from sales of real estate	43,484	18,355	53,943	39,511
Total revenue and other earnings	209,834	136,325	343,204	276,885
Real estate expense	(35,438)	(36,355)	(69,743)	(75,989)
Land development cost of sales	(17,262)	(5,252)	(28,838)	(12,142)
Other expense	(3,182)	(888)	(3,922)	(3,011)
Allocated interest expense	(56,047)	(55,824)	(113,068)	(110,456)
Allocated general and administrative	(18,032)	(16,639)	(36,557)	(34,154)
Segment profit (loss)	79,873	21,367	91,076	41,133
Provision for loan losses	700	19,151	2,206	23,444
Impairment of assets	3,012	1,674	3,012	1,674
Depreciation and amortization	14,474	15,516	29,182	34,017
Capitalized expenditures	46,077	50,983	96,993	83,802
Real estate, net	1,435,920		1,435,920		$ 1,593,983
Real estate available and held for sale	126,070		126,070		137,274
Total real estate	1,561,990		1,561,990		1,731,257
Land and development	1,046,013		1,046,013		1,001,963
Loans receivable and other lending investments, net	1,568,439		1,568,439		1,601,985
Other investments	228,756		228,756		254,172
Total portfolio assets	4,405,198		4,405,198		4,589,377
Cash and other assets	804,199		804,199		1,008,415
Total assets	5,209,397		5,209,397		5,597,792
Stock-based compensation expense	1,633	3,947	6,211	7,186
Land & Development
Segment Reporting
Income from sales of real estate			13,997	2,659
Operating Segments | Real Estate Finance
Segment Reporting
Operating lease income	0	0	0	0
Interest income	34,400	33,729	67,620	68,625
Other income	323	798	1,620	846
Land development revenue	0	0	0	0
Earnings (loss) from equity method investments	0	0	0	0
Income from sales of real estate	0	0	0	0
Total revenue and other earnings	34,723	34,527	69,240	69,471
Real estate expense	0	0	0	0
Land development cost of sales	0	0	0	0
Other expense	(925)	(221)	(839)	(220)
Allocated interest expense	(14,631)	(14,563)	(29,333)	(28,798)
Allocated general and administrative	(3,786)	(3,129)	(7,617)	(6,223)
Segment profit (loss)	15,381	16,614	31,451	34,230
Provision for loan losses	700	19,151	2,206	23,444
Impairment of assets	0	0	0	0
Depreciation and amortization	0	0	0	0
Capitalized expenditures	0	0	0	0
Real estate, net	0		0		0
Real estate available and held for sale	0		0		0
Total real estate	0		0		0
Land and development	0		0		0
Loans receivable and other lending investments, net	1,568,439		1,568,439		1,601,985
Other investments	0		0		0
Total portfolio assets	1,568,439		1,568,439		1,601,985
Operating Segments | Net Lease
Segment Reporting
Operating lease income	36,585	37,781	72,335	74,120
Interest income	0	0	0	0
Other income	433	121	513	124
Land development revenue	0	0	0	0
Earnings (loss) from equity method investments	944	1,666	1,890	3,299
Income from sales of real estate	4,338	5,127	9,267	8,654
Total revenue and other earnings	42,300	44,695	84,005	86,197
Real estate expense	(4,728)	(5,522)	(9,236)	(10,792)
Land development cost of sales	0	0	0	0
Other expense	0	0	0	0
Allocated interest expense	(16,464)	(16,933)	(32,700)	(33,768)
Allocated general and administrative	(4,313)	(3,676)	(8,609)	(7,437)
Segment profit (loss)	16,795	18,564	33,460	34,200
Provision for loan losses	0	0	0	0
Impairment of assets	0	0	0	0
Depreciation and amortization	8,778	9,409	17,629	18,858
Capitalized expenditures	1,625	1,769	2,476	2,114
Real estate, net	1,081,825		1,081,825		1,112,479
Real estate available and held for sale	0		0		0
Total real estate	1,081,825		1,081,825		1,112,479
Land and development	0		0		0
Loans receivable and other lending investments, net	0		0		0
Other investments	67,895		67,895		69,096
Total portfolio assets	1,149,720		1,149,720		1,181,575
Operating Segments | Operating Properties
Segment Reporting
Operating lease income	17,828	18,116	36,909	40,730
Interest income	0	0	0	0
Other income	7,213	10,591	14,557	19,467
Land development revenue	0	0	0	0
Earnings (loss) from equity method investments	31,076	298	30,934	833
Income from sales of real estate	39,146	13,228	44,676	30,857
Total revenue and other earnings	95,263	42,233	127,076	91,887
Real estate expense	(20,796)	(23,940)	(41,916)	(51,364)
Land development cost of sales	0	0	0	0
Other expense	0	0	0	0
Allocated interest expense	(5,849)	(7,057)	(12,469)	(14,725)
Allocated general and administrative	(1,638)	(1,629)	(3,508)	(3,457)
Segment profit (loss)	66,980	9,607	69,183	22,341
Provision for loan losses	0	0	0	0
Impairment of assets	3,012	1,674	3,012	1,674
Depreciation and amortization	5,022	5,446	10,305	13,791
Capitalized expenditures	12,446	21,749	28,243	31,843
Real estate, net	354,095		354,095		481,504
Real estate available and held for sale	126,070		126,070		137,274
Total real estate	480,165		480,165		618,778
Land and development	0		0		0
Loans receivable and other lending investments, net	0		0		0
Other investments	13,065		13,065		11,124
Total portfolio assets	493,230		493,230		629,902
Operating Segments | Land & Development
Segment Reporting
Operating lease income	105	255	211	441
Interest income	0	0	0	0
Other income	1,167	154	2,232	787
Land development revenue	27,888	6,543	42,835	14,801
Earnings (loss) from equity method investments	2,688	4,463	9,348	7,072
Income from sales of real estate	0	0	0	0
Total revenue and other earnings	31,848	11,415	54,626	23,101
Real estate expense	(9,914)	(6,893)	(18,591)	(13,833)
Land development cost of sales	(17,262)	(5,252)	(28,838)	(12,142)
Other expense	0	0	0	0
Allocated interest expense	(8,668)	(7,876)	(17,027)	(15,420)
Allocated general and administrative	(3,327)	(2,733)	(6,597)	(5,526)
Segment profit (loss)	(7,323)	(11,339)	(16,427)	(23,820)
Provision for loan losses	0	0	0	0
Impairment of assets	0	0	0	0
Depreciation and amortization	400	390	699	780
Capitalized expenditures	32,006	27,465	66,274	49,845
Real estate, net	0		0		0
Real estate available and held for sale	0		0		0
Total real estate	0		0		0
Land and development	1,046,013		1,046,013		1,001,963
Loans receivable and other lending investments, net	0		0		0
Other investments	88,874		88,874		100,419
Total portfolio assets	1,134,887		1,134,887		1,102,382
Corporate/Other | Corporate/Other
Segment Reporting
Operating lease income	0	0	0	0
Interest income	0	0	0	0
Other income	961	1,097	2,715	2,101
Land development revenue	0	0	0	0
Earnings (loss) from equity method investments	4,739	2,358	5,542	4,128
Income from sales of real estate	0	0	0	0
Total revenue and other earnings	5,700	3,455	8,257	6,229
Real estate expense	0	0	0	0
Land development cost of sales	0	0	0	0
Other expense	(2,257)	(667)	(3,083)	(2,791)
Allocated interest expense	(10,435)	(9,395)	(21,539)	(17,745)
Allocated general and administrative	(4,968)	(5,472)	(10,226)	(11,511)
Segment profit (loss)	(11,960)	(12,079)	(26,591)	(25,818)
Provision for loan losses	0	0	0	0
Impairment of assets	0	0	0	0
Depreciation and amortization	274	271	549	588
Capitalized expenditures	0	$ 0	0	$ 0
Real estate, net	0		0		0
Real estate available and held for sale	0		0		0
Total real estate	0		0		0
Land and development	0		0		0
Loans receivable and other lending investments, net	0		0		0
Other investments	58,922		58,922		73,533
Total portfolio assets	$ 58,922		$ 58,922		$ 73,533