Use of Special Purpose Entities (SPE) and Variable Interest Entities (VIE)-Assets and Liabilities of Campus Lodge (Details) - USD ($) $ in Thousands		Dec. 31, 2020	Nov. 12, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other assets		$ 165,824		$ 169,214
Total assets	[1]	4,655,587		23,483,369
Other liabilities		138,498		177,260
Total liabilities	[1]	2,348,014		21,278,340
Non-controlling interest		6,371		(704)
Equity		2,307,573		2,205,029	$ 1,180,293	$ 976,001
VIE, Primary Beneficiary
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total assets		2,150,984		19,270,384
Total liabilities		$ 1,667,306		$ 17,878,314
VIE, Primary Beneficiary | Campus Lodge
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash			$ 327
Operating real estate			50,481
Lease intangible			1,619
Other assets			1,395
Total assets			53,822
Mortgages payable in consolidated variable interest entities			36,752
Other liabilities			1,543
Total liabilities			38,295
Non-controlling interest			6,808
Equity			$ 8,719

[1] Our consolidated balance sheets include assets and liabilities of consolidated variable interest entities (“VIEs”) as the Company is the primary beneficiary of these VIEs. As of December 31, 2020 and December 31, 2019, assets of consolidated VIEs totaled $2,150,984 and $19,270,384, respectively, and the liabilities of consolidated VIEs totaled $1,667,306 and $17,878,314, respectively. See Note 7 for further discussion.