Quarterly Financial Data (Unaudited) - Schedule of Cash Flow Statement (Details) - USD ($) $ in Thousands	3 Months Ended							6 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2021	Jun. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
CASH FLOWS FROM OPERATING ACTIVITIES
Net income												$ 26,030	$ (65,718)	$ 23,234
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation and amortization												123,439	147,229	122,580
Straight-line rents												(6,726)	(4,869)	(4,185)
Noncash lease expense												3,721	3,392	0
Net unrealized holding gains on investments												(51,925)	(72,391)	0
Distributions of operating income from unconsolidated affiliates												3,828	3,286	11,273
Equity in (earnings) losses of unconsolidated affiliates												(5,330)	3,057	(5,899)
Stock compensation expense												12,430	10,912	10,006
Amortization of financing costs												4,396	5,038	6,718
Impairment charges												9,925	85,598	1,721
Allowance for credit loss												(2,796)	24,569	2,742
Termination of ground lease												(3,615)	0	0
Adjustments to straight-line rent reserves												2,682	21,871	1,961
Other, net												(5,304)	(8,155)	(11,575)
Changes in assets and liabilities:
Other liabilities												7,856	(3,959)	(4,850)
Lease liability - operating leases												(3,636)	(1,579)	2,014
Prepaid expenses and other assets												(7,427)	4	8,206
Rents receivable												7,384	(28,321)	1,089
Accounts payable and accrued expenses												572	3,005	1,705
Net cash provided by operating activities												104,983	103,947	131,382
CASH FLOWS FROM INVESTING ACTIVITIES
Acquisition of real estate												(161,846)	(21,208)	(319,673)
Development, construction and property improvement costs												(40,671)	(36,579)	(89,385)
Proceeds from the disposition of properties, net												63,901	20,930	88,738
Investments in and advances to unconsolidated affiliates and other												(14,835)	(14,483)	(164,922)
Return of capital from unconsolidated affiliates and other												17,722	14,686	106,005
Issuance of notes receivable												(57,895)	(59,000)	(3,608)
Return of deposits for properties under contract												0	187	2,870
Payment of deferred leasing costs												(4,914)	(6,407)	(6,782)
Net cash used in investing activities												(198,538)	(100,924)	(410,538)
CASH FLOWS FROM FINANCING ACTIVITIES
Principal payments on mortgage and other notes												(98,602)	(51,949)	(158,211)
Principal payments on unsecured debt												(206,781)	(136,490)	(521,600)
Proceeds received on mortgage and other notes												56,847	5,351	324,995
Proceeds from unsecured debt												323,200	236,804	526,400
Payments of finance lease obligations												(63)	(903)	(2,749)
Proceeds from the sale (repurchase) of Common Shares												63,876	(22,386)	145,498
Capital contributions from noncontrolling interests												30,164	52,174	161,365
Distributions to noncontrolling interests												(30,410)	(31,461)	(101,364)
Dividends paid to Common Shareholders												(39,476)	(50,182)	(93,902)
Deferred financing and other costs												(7,436)	(2,215)	(6,476)
Net cash provided by financing activities												91,319	(1,257)	273,956
Increase (decrease) in cash and restricted cash												(2,236)	1,766	(5,200)
Cash of $14,149 and restricted cash of $13,880 beginning of period			$ 29,795				$ 28,029	$ 29,795	$ 28,029	$ 29,795	$ 28,029	29,795	28,029	33,229
Cash of $32,534 and restricted cash of $13,465 end of period				$ 29,795								27,559	29,795	28,029
Previously Reported
CASH FLOWS FROM OPERATING ACTIVITIES
Net income	$ 31,557	$ 1,231	1,860	(32,616)	$ (38,289)	$ 64,906	(60,039)	3,091	4,867	34,648	(33,422)		(66,038)	21,204
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation and amortization			31,390				33,377	62,735	67,170	93,601	101,627		149,793	125,443
Straight-line rents			1,128					2,765		4,244			5,096	0
Noncash lease expense			1,041					2,066		2,887			3,392
Net unrealized holding gains on investments			(6,135)					(8,565)	(64,937)	(55,796)	(57,031)		(72,391)
Distributions of operating income from unconsolidated affiliates			390				1,898	1,387	2,206	2,004	2,829		3,286	11,273
Equity in (earnings) losses of unconsolidated affiliates	(644)	(1,106)	(2,263)	1,082	624	786	(1,255)	(3,369)	(469)	(4,013)	155		1,237	(8,922)
Stock compensation expense			4,511				3,819	7,135	6,136	9,780	8,551		10,912	10,957
Amortization of financing costs			1,269				1,763	2,546	2,920	3,901	4,040		5,169	7,577
Impairment charges	9,925	0	0	34,049		0	51,549	0	51,549	9,925	51,549		85,598	1,721
Gain on disposition of properties			(4,612)					(10,521)	(485)	(10,521)	(509)
Credit loss reserves							4,770		16,175		39,882
Allowance for credit loss			3,065					1,238		973			24,770	0
Termination of ground lease								3,615		3,615
Adjustments to straight-line rent reserves			817					511		254			22,074	0
Other, net			2,312				1,107	4,127	2,780	5,319	2,923		(8,753)	(11,627)
Changes in assets and liabilities:
Other liabilities			3,847				(6,844)	3,114	(6,684)	1,833	(7,736)		(4,208)	(4,466)
Lease liability - operating leases			(494)					(1,533)		(2,653)			(1,579)
Prepaid expenses and other assets			(1,859)				(2,107)	487	4,213	5,579	1,435		32	8,198
Rents receivable			2,408				(24)	(2,801)	25,177	(4,104)	31,511		(29,810)	(455)
Accounts payable and accrued expenses			237				(2,327)	(609)	12,222	220	7,015		3,199	1,632
Net cash provided by operating activities			30,934				27,735	51,033	58,500	72,390	81,081		102,565	127,177
CASH FLOWS FROM INVESTING ACTIVITIES
Acquisition of real estate							(19,088)		(21,208)	(63,425)	(21,208)		(21,208)	(319,673)
Development, construction and property improvement costs			(5,425)				(13,333)	(16,620)	(20,533)	(27,197)	(27,949)		(40,483)	(89,270)
Proceeds from the disposition of properties, net			15,703				0	63,901	13,925	63,901	14,182		20,930	88,738
Investments in and advances to unconsolidated affiliates and other			1,725				1,525	3,976	3,270	6,111	3,662		4,291	151,281
Return of capital from unconsolidated affiliates and other			4,377				5,024	7,717	7,151	10,671	9,054		14,686	105,999
Issuance of notes receivable							(59,000)	(15,995)	(59,000)	(57,957)	(59,000)		(59,000)	(3,608)
Return of deposits for properties under contract							200	(1,000)	187		187		187	2,870
Payment of deferred leasing costs			(1,438)				(2,763)	(3,080)	(4,885)	(3,509)	(5,422)		(7,979)	(7,051)
Change in control of previously unconsolidated affiliate							0		950		950
Net cash used in investing activities			11,492				(90,485)	30,947	(86,683)	(83,627)	(92,868)		(96,208)	(397,057)
CASH FLOWS FROM FINANCING ACTIVITIES
Principal payments on mortgage and other notes			(20,406)				(1,488)	(52,408)	(14,360)	(69,766)	(18,981)		(55,449)	(168,211)
Principal payments on unsecured debt			(33,250)				(5,000)	(102,800)	(69,930)	(160,387)	(123,750)		(136,490)	(521,600)
Proceeds received on mortgage and other notes			3,809				689	8,818	3,340	12,654	5,523		7,261	326,268
Proceeds from unsecured debt			536				122,245	49,295	181,700	211,854	215,554		236,804	526,400
Payments of finance lease obligations							(625)		(833)	(63)	(903)		(903)	(2,749)
Proceeds from the sale (repurchase) of Common Shares							(22,352)	45,675	(22,386)	45,865	(22,386)		(22,386)	145,498
Capital contributions from noncontrolling interests			11,241				7,268	17,109	28,309	26,627	36,736		52,674	161,628
Distributions to noncontrolling interests			(6,800)				(4,914)	(12,202)	(8,178)	(23,781)	(28,418)		(31,461)	(101,370)
Dividends paid to Common Shareholders							(25,245)	(12,945)	(50,182)	(26,208)	(50,182)		(50,182)	(93,902)
Deferred financing and other costs			(333)				(222)	(6,707)	(960)	(7,296)	(1,635)		(2,311)	(6,920)
Net cash provided by financing activities			(45,203)				70,356	(66,165)	46,520	9,499	11,558		(2,443)	265,042
Increase (decrease) in cash and restricted cash			(2,777)				7,606	15,815	18,337	(1,738)	(229)		3,914	(4,838)
Cash of $14,149 and restricted cash of $13,880 beginning of period	49,739	31,147	33,924	29,781	48,347	37,616	30,010	33,924	30,010	33,924	30,010	33,924	30,010	34,848
Cash of $32,534 and restricted cash of $13,465 end of period	32,186	49,739	31,147	33,924	29,781	48,347	37,616	49,739	48,347	32,186	29,781		33,924	30,010
Adjustments
CASH FLOWS FROM OPERATING ACTIVITIES
Net income	(485)	(779)	(1,163)	(309)	446	(2,101)	2,284	(1,942)	183	(2,427)	629		320	2,030
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation and amortization			(750)				(729)	(1,555)	(1,145)	(2,357)	(1,842)		(2,564)	(2,863)
Straight-line rents			(36)				1,094	(80)	2,807	(137)	3,861		(227)	(4,185)
Noncash lease expense							619		1,368	0	2,382		0
Net unrealized holding gains on investments										0			0
Distributions of operating income from unconsolidated affiliates										0			0	0
Equity in (earnings) losses of unconsolidated affiliates	272	207	381	446	612	394	368	588	762	860	1,374		1,820	3,023
Stock compensation expense										0			0	(951)
Amortization of financing costs			(18)				(42)	(36)	(71)	(239)	(99)		(131)	(859)
Impairment charges		0	0	0		0	0	0	0		0		0	0
Gain on disposition of properties										0
Credit loss reserves							(4,770)		(16,175)		(39,882)
Allowance for credit loss			(123)				1,238	(144)	9,620	(200)	20,381		(201)	2,742
Termination of ground lease										0
Adjustments to straight-line rent reserves			79				967	73	6,404	66	19,483		(203)	1,961
Other, net			(1,386)				(1)	(2,258)	(3)	(3,060)	306		(598)	52
Changes in assets and liabilities:
Other liabilities			(48)				122	(74)	175	(85)	153		249	384
Lease liability - operating leases							(376)		(807)	0	(957)		0	2,014
Prepaid expenses and other assets			105				177	(37)	343	102	164		(28)	8
Rents receivable			(90)				(2,457)	24	(3,943)	(14)	(4,735)		1,489	1,544
Accounts payable and accrued expenses			275				24	267	(2,375)	269	53		(194)	73
Net cash provided by operating activities			40				892	(472)	(1,265)	(1,004)	2,079		1,382	4,205
CASH FLOWS FROM INVESTING ACTIVITIES
Acquisition of real estate										0			0
Development, construction and property improvement costs			(46)				(489)	(880)	(1,555)	(1,262)	(1,064)		(3,904)	115
Proceeds from the disposition of properties, net							0			0			0
Investments in and advances to unconsolidated affiliates and other			336				951	647	1,289	921	2,023		(10,192)	13,641
Return of capital from unconsolidated affiliates and other			1,000					1,000		1,400				6
Issuance of notes receivable										0			0
Return of deposits for properties under contract													0
Payment of deferred leasing costs			(410)				17	(360)	(1,631)	(318)	(1,620)		1,572	269
Change in control of previously unconsolidated affiliate							0
Net cash used in investing activities			1,120				(479)	1,593	1,897	2,059	661		(4,716)	(13,481)
CASH FLOWS FROM FINANCING ACTIVITIES
Principal payments on mortgage and other notes										0			3,500	27,627
Principal payments on unsecured debt										0			0
Proceeds received on mortgage and other notes			(2,990)					(2,990)	(1,000)	(2,990)	(1,910)		(1,910)	(18,900)
Proceeds from unsecured debt										0			0
Payments of finance lease obligations										0			0
Proceeds from the sale (repurchase) of Common Shares										0			0
Capital contributions from noncontrolling interests										0			(500)	(263)
Distributions to noncontrolling interests			(1,000)					(1,000)		(1,400)			0	6
Dividends paid to Common Shareholders										0			0
Deferred financing and other costs										0			96	444
Net cash provided by financing activities			(1,990)					(1,990)	(1,000)	(1,590)	(1,910)		1,186	8,914
Increase (decrease) in cash and restricted cash			(830)				413	(869)	(368)	(535)	830		(2,148)	(362)
Cash of $14,149 and restricted cash of $13,880 beginning of period	(4,998)	(4,959)	(4,129)	(1,151)	(2,349)	(1,568)	(1,981)	(4,129)	(1,981)	(4,129)	(1,981)	(4,129)	(1,981)	(1,619)
Cash of $32,534 and restricted cash of $13,465 end of period	(4,664)	(4,998)	(4,959)	(4,129)	(1,151)	(2,349)	(1,568)	(4,998)	(2,349)	(4,664)	(1,151)		(4,129)	(1,981)
As Restated
CASH FLOWS FROM OPERATING ACTIVITIES
Net income	31,072	452	697	(32,925)	(37,843)	62,805	(57,755)	1,149	5,050	32,221	(32,793)		(65,718)	23,234
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation and amortization			30,640				32,648	61,180	66,025	91,244	99,785		147,229	122,580
Straight-line rents			1,092				1,094	2,685	2,807	4,107	3,861		4,869	(4,185)
Noncash lease expense			1,041				619	2,066	1,368	2,887	2,382		3,392
Net unrealized holding gains on investments			(6,135)					(8,565)	(64,937)	(55,796)	(57,031)		(72,391)
Distributions of operating income from unconsolidated affiliates			390				1,898	1,387	2,206	2,004	2,829		3,286	11,273
Equity in (earnings) losses of unconsolidated affiliates	(372)	(899)	(1,882)	1,528	1,236	1,180	(887)	(2,781)	293	(3,153)	1,529		3,057	(5,899)
Stock compensation expense			4,511				3,819	7,135	6,136	9,780	8,551		10,912	10,006
Amortization of financing costs			1,251				1,721	2,510	2,849	3,662	3,941		5,038	6,718
Impairment charges	9,925	0	0	34,049		0	51,549	0	51,549	9,925	51,549		85,598	1,721
Gain on disposition of properties			(4,612)					(10,521)	(485)	(10,521)	(509)
Credit loss reserves
Allowance for credit loss			2,942				1,238	1,094	9,620	773	20,381		24,569	2,742
Termination of ground lease								3,615		3,615
Adjustments to straight-line rent reserves			896				967	584	6,404	320	19,483		21,871	1,961
Other, net			926				1,106	1,869	2,777	2,259	3,229		(8,155)	(11,575)
Changes in assets and liabilities:
Other liabilities			3,799				(6,722)	3,040	(6,509)	1,748	(7,583)		(3,959)	(4,850)
Lease liability - operating leases			(494)				(376)	(1,533)	(807)	(2,653)	(957)		(1,579)	2,014
Prepaid expenses and other assets			(1,754)				(1,930)	450	4,556	5,681	1,599		4	8,206
Rents receivable			2,318				(2,481)	(2,777)	21,234	(4,118)	26,776		(28,321)	1,089
Accounts payable and accrued expenses			512				(2,303)	(342)	9,847	489	7,068		3,005	1,705
Net cash provided by operating activities			30,974				28,627	50,561	57,235	71,386	83,160		103,947	131,382
CASH FLOWS FROM INVESTING ACTIVITIES
Acquisition of real estate							(19,088)		(21,208)	(63,425)	(21,208)		(21,208)	(319,673)
Development, construction and property improvement costs			(5,379)				(12,844)	(15,740)	(18,978)	(25,935)	(26,885)		(36,579)	(89,385)
Proceeds from the disposition of properties, net			15,703				0	63,901	13,925	63,901	14,182		20,930	88,738
Investments in and advances to unconsolidated affiliates and other			2,061				2,476	4,623	4,559	7,032	5,685		14,483	164,922
Return of capital from unconsolidated affiliates and other			5,377				5,024	8,717	7,151	12,071	9,054		14,686	106,005
Issuance of notes receivable							(59,000)	(15,995)	(59,000)	(57,957)	(59,000)		(59,000)	(3,608)
Return of deposits for properties under contract							200	(1,000)	187		187		187	2,870
Payment of deferred leasing costs			(1,028)				(2,780)	(2,720)	(3,254)	(3,191)	(3,802)		(6,407)	(6,782)
Change in control of previously unconsolidated affiliate							0		950		950
Net cash used in investing activities			12,612				(90,964)	32,540	(84,786)	(81,568)	(92,207)		(100,924)	(410,538)
CASH FLOWS FROM FINANCING ACTIVITIES
Principal payments on mortgage and other notes			(20,406)				(1,488)	(52,408)	(14,360)	(69,766)	(18,981)		(51,949)	(140,584)
Principal payments on unsecured debt			(33,250)				(5,000)	(102,800)	(69,930)	(160,387)	(123,750)		(136,490)	(521,600)
Proceeds received on mortgage and other notes			819				689	5,828	2,340	9,664	3,613		5,351	307,368
Proceeds from unsecured debt			536				122,245	49,295	181,700	211,854	215,554		236,804	526,400
Payments of finance lease obligations							(625)		(833)	(63)	(903)		(903)	(2,749)
Proceeds from the sale (repurchase) of Common Shares							(22,352)	45,675	(22,386)	45,865	(22,386)		(22,386)	145,498
Capital contributions from noncontrolling interests			11,241				7,268	17,109	28,309	26,627	36,736		52,174	161,365
Distributions to noncontrolling interests			(5,800)				(4,914)	(11,202)	(8,178)	(22,381)	(28,418)		(31,461)	(101,364)
Dividends paid to Common Shareholders							(25,245)	(12,945)	(50,182)	(26,208)	(50,182)		(50,182)	(93,902)
Deferred financing and other costs			(333)				(222)	(6,707)	(960)	(7,296)	(1,635)		(2,215)	(6,476)
Net cash provided by financing activities			(47,193)				70,356	(68,155)	45,520	7,909	9,648		(1,257)	273,956
Increase (decrease) in cash and restricted cash			(3,607)				8,019	14,946	17,969	(2,273)	601		1,766	(5,200)
Cash of $14,149 and restricted cash of $13,880 beginning of period	44,741	26,188	29,795	28,630	45,998	36,048	28,029	29,795	28,029	29,795	28,029	$ 29,795	28,029	33,229
Cash of $32,534 and restricted cash of $13,465 end of period	$ 27,522	$ 44,741	$ 26,188	$ 29,795	$ 28,630	$ 45,998	$ 36,048	$ 44,741	$ 45,998	$ 27,522	$ 28,630		$ 29,795	$ 28,029