Business Segments - Summary of Information for Reportable Segments (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Summary information for the reportable segments
Total revenues	$ 173,746	$ 178,124	$ 181,643	$ 186,043	$ 191,831	$ 192,013	$ 190,311	$ 196,447	$ 719,556	$ 770,602	$ 840,247
Other operating expenses not allocated to segments									488,461	383,635	399,377
Total operating expenses									737,497	644,876	664,101
Proportionate property net operating income (loss)									(17,941)	125,726	176,146
Other items included in income (loss) before income tax expense									(1,194)	363,111	506,120
(Loss) income from continuing operations before income tax (expense) benefit and discontinued operations									(19,135)	488,837	682,266
Real Estate
Summary information for the reportable segments
Property operating expenses									249,036	261,241	264,724
Segment Reconciling Items [Member]
Summary information for the reportable segments
Total revenues									44,370	27,235	25,936
Total operating expenses									31,555	25,190	23,842
Proportionate property net operating income (loss)									12,815	2,045	2,094
(Loss) income from continuing operations before income tax (expense) benefit and discontinued operations									12,815	2,045	2,094
Segment Reconciling Items [Member] | Real Estate
Summary information for the reportable segments
Property operating expenses									31,555	25,190	23,842
Corporate Non-Segment [Member]
Summary information for the reportable segments
Total revenues									6,139	40,381	146,026
Other operating expenses not allocated to segments									488,461	383,635	399,377
Total operating expenses									513,656	426,922	455,688
Proportionate property net operating income (loss)									(507,517)	(386,541)	(309,662)
Other items included in income (loss) before income tax expense									(1,194)	363,111	506,120
(Loss) income from continuing operations before income tax (expense) benefit and discontinued operations									(508,711)	(23,430)	196,458
Corporate Non-Segment [Member] | Real Estate
Summary information for the reportable segments
Property operating expenses									25,195	43,287	56,311
Same Store [Member] | Operating Segments [Member]
Summary information for the reportable segments
Total revenues									655,853	689,255	645,917
Total operating expenses									182,967	184,150	174,708
Proportionate property net operating income (loss)									472,886	505,105	471,209
(Loss) income from continuing operations before income tax (expense) benefit and discontinued operations									472,886	505,105	471,209
Same Store [Member] | Operating Segments [Member] | Real Estate
Summary information for the reportable segments
Property operating expenses									182,967	184,150	174,708
Other Real Estate [Member] | Operating Segments [Member]
Summary information for the reportable segments
Total revenues									13,194	13,731	22,368
Total operating expenses									9,319	8,614	9,863
Proportionate property net operating income (loss)									3,875	5,117	12,505
(Loss) income from continuing operations before income tax (expense) benefit and discontinued operations									3,875	5,117	12,505
Other Real Estate [Member] | Operating Segments [Member] | Real Estate
Summary information for the reportable segments
Property operating expenses									$ 9,319	$ 8,614	$ 9,863