Summary of Significant Accounting Policies - Real Estate (Details)	12 Months Ended
Sep. 30, 2019
Minimum
Real Estate Properties [Line Items]
Percentage of sales price (at least)	20.00%
Maximum
Real Estate Properties [Line Items]
Percentage of sales price (at least)	25.00%

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

Name:	us-gaap_RealEstatePropertiesLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration