    <SEC-DOCUMENT>0000860546-21-000019-index.html : 20210429
    <SEC-HEADER>0000860546-21-000019.hdr.sgml : 20210429
    <ACCEPTANCE-DATETIME>20210429162038
    ACCESSION NUMBER:		0000860546-21-000019
    CONFORMED SUBMISSION TYPE:	8-K
    PUBLIC DOCUMENT COUNT:		23
    CONFORMED PERIOD OF REPORT:	20210429
    ITEM INFORMATION:		Results of Operations and Financial Condition
    ITEM INFORMATION:		Financial Statements and Exhibits
    FILED AS OF DATE:		20210429
    DATE AS OF CHANGE:		20210429

    FILER:

    	COMPANY DATA:
    		COMPANY CONFORMED NAME:			CORPORATE OFFICE PROPERTIES TRUST
    		CENTRAL INDEX KEY:			0000860546
    		STANDARD INDUSTRIAL CLASSIFICATION:	REAL ESTATE INVESTMENT TRUSTS [6798]
    		IRS NUMBER:				232947217
    		STATE OF INCORPORATION:			MD
    		FISCAL YEAR END:			1231

    	FILING VALUES:
    		FORM TYPE:		8-K
    		SEC ACT:		1934 Act
    		SEC FILE NUMBER:	001-14023
    		FILM NUMBER:		21870950

    	BUSINESS ADDRESS:
    		STREET 1:		6711 COLUMBIA GATEWAY DRIVE
    		STREET 2:		SUITE 300
    		CITY:			COLUMBIA
    		STATE:			MD
    		ZIP:			21046
    		BUSINESS PHONE:		4432855400

    	MAIL ADDRESS:
    		STREET 1:		6711 COLUMBIA GATEWAY DRIVE
    		STREET 2:		SUITE 300
    		CITY:			COLUMBIA
    		STATE:			MD
    		ZIP:			21046

    	FORMER COMPANY:
    		FORMER CONFORMED NAME:	CORPORATE OFFICE PROPERTIES TRUST INC
    		DATE OF NAME CHANGE:	19980105

    	FORMER COMPANY:
    		FORMER CONFORMED NAME:	ROYALE INVESTMENTS INC
    		DATE OF NAME CHANGE:	19930328

    	FORMER COMPANY:
    		FORMER CONFORMED NAME:	ROYALE REIT INC
    		DATE OF NAME CHANGE:	19600201
    </SEC-HEADER>
    <DOCUMENT>
    <TYPE>8-K
    <SEQUENCE>1
    <FILENAME>ofc-20210429.htm
    <DESCRIPTION>8-K
    <TEXT>
    Document 1 - file: ofc-20210429.htm

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EX-99.1
    <SEQUENCE>2
    <FILENAME>copt3312021ex991.htm
    <DESCRIPTION>EX-99.1
    <TEXT>
    Document 2 - file: copt3312021ex991.htm

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EX-101.SCH
    <SEQUENCE>3
    <FILENAME>ofc-20210429.xsd
    <DESCRIPTION>XBRL TAXONOMY EXTENSION SCHEMA DOCUMENT
    <TEXT>
    Document 3 - file: ofc-20210429.xsd

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EX-101.CAL
    <SEQUENCE>4
    <FILENAME>ofc-20210429_cal.xml
    <DESCRIPTION>XBRL TAXONOMY EXTENSION CALCULATION LINKBASE DOCUMENT
    <TEXT>
    Document 4 - file: ofc-20210429_cal.xml

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EX-101.DEF
    <SEQUENCE>5
    <FILENAME>ofc-20210429_def.xml
    <DESCRIPTION>XBRL TAXONOMY EXTENSION DEFINITION LINKBASE DOCUMENT
    <TEXT>
    Document 5 - file: ofc-20210429_def.xml

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EX-101.LAB
    <SEQUENCE>6
    <FILENAME>ofc-20210429_lab.xml
    <DESCRIPTION>XBRL TAXONOMY EXTENSION LABEL LINKBASE DOCUMENT
    <TEXT>
    Document 6 - file: ofc-20210429_lab.xml

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EX-101.PRE
    <SEQUENCE>7
    <FILENAME>ofc-20210429_pre.xml
    <DESCRIPTION>XBRL TAXONOMY EXTENSION PRESENTATION LINKBASE DOCUMENT
    <TEXT>
    Document 7 - file: ofc-20210429_pre.xml

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>8
    <FILENAME>a2021_q1xcover1a.jpg
    <TEXT>
    Document 8 - file: a2021_q1xcover1a.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>9
    <FILENAME>chart-1b0cebc0d9ac4cd79f61a.jpg
    <TEXT>
    Document 9 - file: chart-1b0cebc0d9ac4cd79f61a.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>10
    <FILENAME>chart-2bc2c322ee364e5d9841a.jpg
    <TEXT>
    Document 10 - file: chart-2bc2c322ee364e5d9841a.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>11
    <FILENAME>chart-6742c5df10b942e0a861a.jpg
    <TEXT>
    Document 11 - file: chart-6742c5df10b942e0a861a.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>12
    <FILENAME>chart-8d8a59a950c34135a141a.jpg
    <TEXT>
    Document 12 - file: chart-8d8a59a950c34135a141a.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>13
    <FILENAME>chart-edeb4c7103414bbf9701a.jpg
    <TEXT>
    Document 13 - file: chart-edeb4c7103414bbf9701a.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>14
    <FILENAME>logo2dtd021015a01a181a.jpg
    <TEXT>
    Document 14 - file: logo2dtd021015a01a181a.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>15
    <FILENAME>tableofcontents_q121-1a.jpg
    <TEXT>
    Document 15 - file: tableofcontents_q121-1a.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>XML
    <SEQUENCE>16
    <FILENAME>ofc-20210429_htm.xml
    <DESCRIPTION>IDEA: XBRL DOCUMENT
    <TEXT>
    Document 16 - file: ofc-20210429_htm.html

    Document 16 - RAW XML: ofc-20210429_htm.xml

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>XML
    <SEQUENCE>17
    <FILENAME>R1.htm
    <DESCRIPTION>IDEA: XBRL DOCUMENT
    <TEXT>
    Document 17 - file: R1.htm

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EXCEL
    <SEQUENCE>18
    <FILENAME>Financial_Report.xlsx
    <DESCRIPTION>IDEA: XBRL DOCUMENT
    <TEXT>
    Document 18 - file: Financial_Report.xlsx

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>XML
    <SEQUENCE>19
    <FILENAME>Show.js
    <DESCRIPTION>IDEA: XBRL DOCUMENT
    <TEXT>
    Document 19 - file: Show.js

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>XML
    <SEQUENCE>20
    <FILENAME>report.css
    <DESCRIPTION>IDEA: XBRL DOCUMENT
    <TEXT>
    Document 20 - file: report.css

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>XML
    <SEQUENCE>21
    <FILENAME>FilingSummary.xml
    <DESCRIPTION>IDEA: XBRL DOCUMENT
    <TEXT>
    Document 21 - file: FilingSummary.html

    Document 21 - RAW XML: FilingSummary.xml

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>JSON
    <SEQUENCE>23
    <FILENAME>MetaLinks.json
    <DESCRIPTION>IDEA: XBRL DOCUMENT
    <TEXT>
    Document 23 - file: MetaLinks.json

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>ZIP
    <SEQUENCE>24
    <FILENAME>0000860546-21-000019-xbrl.zip
    <DESCRIPTION>IDEA: XBRL DOCUMENT
    <TEXT>
    Document 24 - file: 0000860546-21-000019-xbrl.zip

    </DOCUMENT>
    </SEC-DOCUMENT>