Loans Receivable - Narrative (Details) $ in Thousands, £ in Millions	3 Months Ended
Jun. 30, 2021 USD ($)	Jun. 30, 2021 GBP (£)	Dec. 31, 2020 USD ($)
Financing Receivable, Troubled Debt Restructuring [Line Items]
Interest receivable	$ 21,938		$ 15,615
Financing receivable	1,295,663
Safanad
Financing Receivable, Troubled Debt Restructuring [Line Items]
Financing receivable	$ 750,330	£ 540
Working capital facility \| £		£ 30
Term of receivable	5 years

Amount, after allowance for credit loss, of financing receivable. Excludes financing receivable covered under loss sharing agreement.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 50
-Paragraph 5
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=124255953&loc=SL82919230-210447

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(3))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=124259787&loc=d3e4428-111522

Name:	us-gaap_NotesReceivableNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant