Number of shares of common stock outstanding. Common stock represent the ownership interest in a corporation.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21463-112644

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(29))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

+ Details

Name:	us-gaap_CommonStockSharesOutstanding
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

The equity interest of noncontrolling shareholders, partners or other equity holders in consolidated entity.

+ References

No definition available.

+ Details

Name:	us-gaap_MinorityInterestOwnershipPercentageByNoncontrollingOwners
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

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.

+ References

No definition available.

+ Details

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

- Definition

Per share amount received by subsidiary or equity investee for each share of common stock issued or sold in the stock transaction.

+ References

No definition available.

+ Details

Name:	us-gaap_SaleOfStockPricePerShare
Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	instant

Related Person Transactions - Additional Information (Details) - $ / shares	Sep. 30, 2020	Feb. 13, 2020	Sep. 30, 2019	Jul. 01, 2019
Related Party Transaction [Line Items]
Common stock shares outstanding (in shares)	15,000,000		15,000,000
ABP Trust \| Class A common shares
Related Party Transaction [Line Items]
Common stock shares outstanding (in shares)	157,502
ABP Trust \| Class A units
Related Party Transaction [Line Items]
Common stock shares outstanding (in shares)	15,000,000
Five Star
Related Party Transaction [Line Items]
Ownership percentage by noncontrolling owners	6.40%
SVC
Related Party Transaction [Line Items]
Ownership percentage by noncontrolling owners	1.10%
ILPT
Related Party Transaction [Line Items]
Ownership percentage by noncontrolling owners	1.20%
OPI
Related Party Transaction [Line Items]
Ownership percentage by noncontrolling owners	1.50%
DHC
Related Party Transaction [Line Items]
Ownership percentage by noncontrolling owners	1.10%
TA
Related Party Transaction [Line Items]
Ownership percentage by noncontrolling owners	4.60%
RMRM
Related Party Transaction [Line Items]
Ownership percentage by noncontrolling owners	2.30%
TRMT
Related Party Transaction [Line Items]
Ownership percentage by noncontrolling owners	19.40%
AIC \| ABP Trust
Related Party Transaction [Line Items]
Ownership percentage by noncontrolling owners		14.30%
Centre Street \| ABP Trust
Related Party Transaction [Line Items]
Ownership percentage by noncontrolling owners	100.00%
Underwritten Public Offering \| DHC, OPI and SVC
Related Party Transaction [Line Items]
Number of shares issued (in dollars per share)				$ 40.00