Segment Reporting - Schedule of Segments (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019 USD ($)	Jun. 30, 2018 USD ($)	Jun. 30, 2019 USD ($) segments	Jun. 30, 2018 USD ($)	May 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Segment Reporting [Abstract]
Number of reportable segments | segments			4
Segment profit (loss)
Revenues	$ 98,468	$ 171,571	$ 205,270	$ 535,814
Earnings (losses) from equity method investments	3,640	(7,278)	8,949	(3,946)
Selling profit from sales-type leases	180,416	0	180,416	0
Gain on consolidation of equity method investment	0	67,877	0	67,877
Income from sales of real estate	220,523	56,895	229,930	73,943
Total revenue and other earnings	503,047	289,065	624,565	673,688
Other expense	(11,883)	(3,716)	(12,391)	(4,882)
Allocated interest expense	(43,752)	(43,172)	(90,329)	(88,353)
Allocated general and administrative	(17,598)	(19,725)	(34,448)	(39,448)
Segment profit (loss)	398,540	102,048	415,735	161,013
Other significant items:
Provision for loan losses	110	18,892	13	18,037
Impairment of assets	1,102	6,088	4,953	10,188
Depreciation and amortization	13,718	10,767	29,386	21,878
Capitalized expenditures	33,165	47,946	72,417	87,572
Segment assets
Real estate, net	1,421,602		1,421,602			$ 1,771,019
Real estate available and held for sale	12,770		12,770			22,551
Total real estate	1,434,372		1,434,372			1,793,570
Net investment in leases	421,842		421,842		$ 424,100	0
Land and development, net	668,656		668,656			598,218
Loans receivable and other lending investments, net	902,146		902,146			988,224
Other investments	564,170		564,170			304,275
Total portfolio assets	3,991,186		3,991,186			3,684,287
Cash and other assets	774,841		774,841			1,329,990
Total assets	4,766,027		4,766,027			5,014,277
Stock-based compensation expense	9,705	3,503	13,954	12,593
Operating lease income
Segment profit (loss)
Revenues	55,185	44,609	114,100	90,407
Interest income
Segment profit (loss)
Revenues	20,341	25,212	40,716	51,909
Interest income from sales-type leases
Segment profit (loss)
Revenues	3,817	0	3,817	0
Other income
Segment profit (loss)
Revenues	10,050	20,823	24,863	36,142
Land development
Segment profit (loss)
Revenues	9,075	80,927	21,774	357,356
Cost of sales expense	(9,236)	(83,361)	(23,684)	(306,768)
Real estate
Segment profit (loss)
Cost of sales expense	(22,038)	(37,043)	(47,978)	(73,224)
Operating Segments | Real Estate Finance
Segment profit (loss)
Earnings (losses) from equity method investments	0	0	0	0
Selling profit from sales-type leases	0		0
Gain on consolidation of equity method investment		0		0
Income from sales of real estate	0	0	0	0
Total revenue and other earnings	20,465	28,345	43,029	55,425
Other expense	(47)	(290)	(311)	(690)
Allocated interest expense	(7,936)	(10,648)	(16,349)	(22,413)
Allocated general and administrative	(2,279)	(3,852)	(4,488)	(7,821)
Segment profit (loss)	10,203	13,555	21,881	24,501
Other significant items:
Provision for loan losses	110	18,892	13	18,037
Impairment of assets	0	0	0	0
Depreciation and amortization	0	0	0	0
Capitalized expenditures	0	0	0	0
Segment assets
Real estate, net	0		0			0
Real estate available and held for sale	0		0			0
Total real estate	0		0			0
Net investment in leases	0		0
Land and development, net	0		0			0
Loans receivable and other lending investments, net	858,061		858,061			988,224
Other investments	0		0			0
Total portfolio assets	858,061		858,061			988,224
Operating Segments | Real Estate Finance | Operating lease income
Segment profit (loss)
Revenues	0	0	0	0
Operating Segments | Real Estate Finance | Interest income
Segment profit (loss)
Revenues	19,933	25,212	40,308	51,909
Operating Segments | Real Estate Finance | Interest income from sales-type leases
Segment profit (loss)
Revenues	0		0
Operating Segments | Real Estate Finance | Other income
Segment profit (loss)
Revenues	532	3,133	2,721	3,516
Operating Segments | Real Estate Finance | Land development
Segment profit (loss)
Revenues	0	0	0	0
Cost of sales expense	0	0	0	0
Operating Segments | Real Estate Finance | Real estate
Segment profit (loss)
Cost of sales expense	0	0	0	0
Operating Segments | Net Lease
Segment profit (loss)
Earnings (losses) from equity method investments	3,582	2,694	10,812	6,252
Selling profit from sales-type leases	180,416		180,416
Gain on consolidation of equity method investment		67,877		67,877
Income from sales of real estate	219,742	24,493	219,742	24,907
Total revenue and other earnings	459,562	125,072	519,696	159,818
Other expense	0	0	0	0
Allocated interest expense	(23,606)	(13,591)	(45,372)	(27,792)
Allocated general and administrative	(6,734)	(4,853)	(12,412)	(9,439)
Segment profit (loss)	423,453	103,195	450,038	115,176
Other significant items:
Provision for loan losses	0	0	0	0
Impairment of assets	0	4,342	0	4,342
Depreciation and amortization	12,272	6,341	25,832	12,652
Capitalized expenditures	2,105	720	4,861	1,198
Segment assets
Real estate, net	1,249,824		1,249,824			1,536,494
Real estate available and held for sale	0		0			1,055
Total real estate	1,249,824		1,249,824			1,537,549
Net investment in leases	421,842		421,842
Land and development, net	0		0			0
Loans receivable and other lending investments, net	44,085		44,085			0
Other investments	408,257		408,257			165,804
Total portfolio assets	2,124,008		2,124,008			1,703,353
Operating Segments | Net Lease | Operating lease income
Segment profit (loss)
Revenues	48,660	29,310	98,143	59,036
Operating Segments | Net Lease | Interest income
Segment profit (loss)
Revenues	408	0	408	0
Operating Segments | Net Lease | Interest income from sales-type leases
Segment profit (loss)
Revenues	3,817		3,817
Operating Segments | Net Lease | Other income
Segment profit (loss)
Revenues	2,937	698	6,358	1,746
Operating Segments | Net Lease | Land development
Segment profit (loss)
Revenues	0	0	0	0
Cost of sales expense	0	0	0	0
Operating Segments | Net Lease | Real estate
Segment profit (loss)
Cost of sales expense	(5,769)	(3,433)	(11,874)	(7,411)
Operating Segments | Operating Properties
Segment profit (loss)
Earnings (losses) from equity method investments	(2,630)	(1,316)	(5,040)	(2,591)
Selling profit from sales-type leases	0		0
Gain on consolidation of equity method investment		0		0
Income from sales of real estate	781	32,402	10,188	49,036
Total revenue and other earnings	8,580	59,636	27,307	102,957
Other expense	0	0	0	0
Allocated interest expense	(2,548)	(4,578)	(5,466)	(10,106)
Allocated general and administrative	(726)	(1,975)	(1,487)	(4,018)
Segment profit (loss)	(2,982)	29,265	1,033	43,390
Other significant items:
Provision for loan losses	0	0	0	0
Impairment of assets	2	446	3,853	4,546
Depreciation and amortization	900	3,738	2,457	7,664
Capitalized expenditures	1,646	4,623	2,063	12,324
Segment assets
Real estate, net	171,778		171,778			234,525
Real estate available and held for sale	12,770		12,770			21,496
Total real estate	184,548		184,548			256,021
Net investment in leases	0		0
Land and development, net	0		0			0
Loans receivable and other lending investments, net	0		0			0
Other investments	69,208		69,208			65,643
Total portfolio assets	253,756		253,756			321,664
Operating Segments | Operating Properties | Operating lease income
Segment profit (loss)
Revenues	6,455	15,199	15,810	31,016
Operating Segments | Operating Properties | Interest income
Segment profit (loss)
Revenues	0	0	0	0
Operating Segments | Operating Properties | Interest income from sales-type leases
Segment profit (loss)
Revenues	0		0
Operating Segments | Operating Properties | Other income
Segment profit (loss)
Revenues	3,974	13,351	6,349	25,496
Operating Segments | Operating Properties | Land development
Segment profit (loss)
Revenues	0	0	0	0
Cost of sales expense	0	0	0	0
Operating Segments | Operating Properties | Real estate
Segment profit (loss)
Cost of sales expense	(8,288)	(23,818)	(19,321)	(45,443)
Operating Segments | Land and Development
Segment profit (loss)
Earnings (losses) from equity method investments	2,924	1,023	3,211	2,566
Selling profit from sales-type leases	0		0
Gain on consolidation of equity method investment		0		0
Income from sales of real estate	0	0	0	0
Total revenue and other earnings	13,380	83,363	29,887	362,061
Other expense	0	0	0	0
Allocated interest expense	(5,493)	(5,308)	(10,620)	(11,781)
Allocated general and administrative	(2,923)	(3,747)	(6,180)	(7,552)
Segment profit (loss)	(12,253)	(18,845)	(27,380)	15,590
Other significant items:
Provision for loan losses	0	0	0	0
Impairment of assets	1,100	1,300	1,100	1,300
Depreciation and amortization	244	318	490	832
Capitalized expenditures	29,414	42,603	65,493	74,050
Segment assets
Real estate, net	0		0			0
Real estate available and held for sale	0		0			0
Total real estate	0		0			0
Net investment in leases	0		0
Land and development, net	668,656		668,656			598,218
Loans receivable and other lending investments, net	0		0			0
Other investments	42,750		42,750			65,312
Total portfolio assets	711,406		711,406			663,530
Operating Segments | Land and Development | Operating lease income
Segment profit (loss)
Revenues	70	100	147	355
Operating Segments | Land and Development | Interest income
Segment profit (loss)
Revenues	0	0	0	0
Operating Segments | Land and Development | Interest income from sales-type leases
Segment profit (loss)
Revenues	0		0
Operating Segments | Land and Development | Other income
Segment profit (loss)
Revenues	1,311	1,313	4,755	1,784
Operating Segments | Land and Development | Land development
Segment profit (loss)
Revenues	9,075	80,927	21,774	357,356
Cost of sales expense	(9,236)	(83,361)	(23,684)	(306,768)
Operating Segments | Land and Development | Real estate
Segment profit (loss)
Cost of sales expense	(7,981)	(9,792)	(16,783)	(20,370)
Corporate/Other
Segment profit (loss)
Earnings (losses) from equity method investments	(236)	(9,679)	(34)	(10,173)
Selling profit from sales-type leases	0		0
Gain on consolidation of equity method investment		0		0
Income from sales of real estate	0	0	0	0
Total revenue and other earnings	1,060	(7,351)	4,646	(6,573)
Other expense	(11,836)	(3,426)	(12,080)	(4,192)
Allocated interest expense	(4,169)	(9,047)	(12,522)	(16,261)
Allocated general and administrative	(4,936)	(5,298)	(9,881)	(10,618)
Segment profit (loss)	(19,881)	(25,122)	(29,837)	(37,644)
Other significant items:
Provision for loan losses	0	0	0	0
Impairment of assets	0	0	0	0
Depreciation and amortization	302	370	607	730
Capitalized expenditures	0	0	0	0
Segment assets
Real estate, net	0		0			0
Real estate available and held for sale	0		0			0
Total real estate	0		0			0
Net investment in leases	0		0
Land and development, net	0		0			0
Loans receivable and other lending investments, net	0		0			0
Other investments	43,955		43,955			7,516
Total portfolio assets	43,955		43,955			$ 7,516
Corporate/Other | Operating lease income
Segment profit (loss)
Revenues	0	0	0	0
Corporate/Other | Interest income
Segment profit (loss)
Revenues	0	0	0	0
Corporate/Other | Interest income from sales-type leases
Segment profit (loss)
Revenues	0		0
Corporate/Other | Other income
Segment profit (loss)
Revenues	1,296	2,328	4,680	3,600
Corporate/Other | Land development
Segment profit (loss)
Revenues	0	0	0	0
Cost of sales expense	0	0	0	0
Corporate/Other | Real estate
Segment profit (loss)
Cost of sales expense	$ 0	$ 0	$ 0	$ 0