    <SEC-DOCUMENT>0000874238-21-000059-index.html : 20210630
    <SEC-HEADER>0000874238-21-000059.hdr.sgml : 20210630
    <ACCEPTANCE-DATETIME>20210630161556
    ACCESSION NUMBER:		0000874238-21-000059
    CONFORMED SUBMISSION TYPE:	8-K
    PUBLIC DOCUMENT COUNT:		34
    CONFORMED PERIOD OF REPORT:	20210628
    ITEM INFORMATION:		Entry into a Material Definitive Agreement
    ITEM INFORMATION:		Other Events
    ITEM INFORMATION:		Financial Statements and Exhibits
    FILED AS OF DATE:		20210630
    DATE AS OF CHANGE:		20210630

    FILER:

    	COMPANY DATA:
    		COMPANY CONFORMED NAME:			STERLING CONSTRUCTION CO INC
    		CENTRAL INDEX KEY:			0000874238
    		STANDARD INDUSTRIAL CLASSIFICATION:	HEAVY CONSTRUCTION OTHER THAN BUILDING CONST - CONTRACTORS [1600]
    		IRS NUMBER:				251655321
    		STATE OF INCORPORATION:			DE
    		FISCAL YEAR END:			1231

    	FILING VALUES:
    		FORM TYPE:		8-K
    		SEC ACT:		1934 Act
    		SEC FILE NUMBER:	001-31993
    		FILM NUMBER:		211062108

    	BUSINESS ADDRESS:
    		STREET 1:		1800 HUGHES LANDING BLVD.
    		STREET 2:		SUITE 250
    		CITY:			THE WOODLANDS
    		STATE:			TX
    		ZIP:			77380
    		BUSINESS PHONE:		281-214-0800

    	MAIL ADDRESS:
    		STREET 1:		1800 HUGHES LANDING BLVD.
    		STREET 2:		SUITE 250
    		CITY:			THE WOODLANDS
    		STATE:			TX
    		ZIP:			77380

    	FORMER COMPANY:
    		FORMER CONFORMED NAME:	OAKHURST CO INC
    		DATE OF NAME CHANGE:	19950831

    	FORMER COMPANY:
    		FORMER CONFORMED NAME:	OAKHURST CAPITAL INC
    		DATE OF NAME CHANGE:	19931130
    </SEC-HEADER>
    <DOCUMENT>
    <TYPE>8-K
    <SEQUENCE>1
    <FILENAME>strl-20210628.htm
    <DESCRIPTION>8-K
    <TEXT>
    Document 1 - file: strl-20210628.htm

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EX-10.1
    <SEQUENCE>2
    <FILENAME>a20210630ex101secondamendm.htm
    <DESCRIPTION>EX-10.1
    <TEXT>
    Document 2 - file: a20210630ex101secondamendm.htm

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EX-99.1
    <SEQUENCE>3
    <FILENAME>a20210630ex991debtamendmen.htm
    <DESCRIPTION>EX-99.1
    <TEXT>
    Document 3 - file: a20210630ex991debtamendmen.htm

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EX-101.SCH
    <SEQUENCE>4
    <FILENAME>strl-20210628.xsd
    <DESCRIPTION>XBRL TAXONOMY EXTENSION SCHEMA DOCUMENT
    <TEXT>
    Document 4 - file: strl-20210628.xsd

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EX-101.LAB
    <SEQUENCE>5
    <FILENAME>strl-20210628_lab.xml
    <DESCRIPTION>XBRL TAXONOMY EXTENSION LABEL LINKBASE DOCUMENT
    <TEXT>
    Document 5 - file: strl-20210628_lab.xml

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EX-101.PRE
    <SEQUENCE>6
    <FILENAME>strl-20210628_pre.xml
    <DESCRIPTION>XBRL TAXONOMY EXTENSION PRESENTATION LINKBASE DOCUMENT
    <TEXT>
    Document 6 - file: strl-20210628_pre.xml

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>7
    <FILENAME>bmo_sterling-secondamendme.jpg
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 7 - file: bmo_sterling-secondamendme.jpg

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

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>9
    <FILENAME>bmo_sterling-secondamendmeb.jpg
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 9 - file: bmo_sterling-secondamendmeb.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>10
    <FILENAME>bmo_sterling-secondamendmec.jpg
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 10 - file: bmo_sterling-secondamendmec.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>11
    <FILENAME>bmo_sterling-secondamendmed.jpg
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 11 - file: bmo_sterling-secondamendmed.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>12
    <FILENAME>bmo_sterling-secondamendmee.jpg
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 12 - file: bmo_sterling-secondamendmee.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>13
    <FILENAME>bmo_sterling-secondamendmef.jpg
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 13 - file: bmo_sterling-secondamendmef.jpg

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

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>15
    <FILENAME>bmo_sterling-secondamendmeh.jpg
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 15 - file: bmo_sterling-secondamendmeh.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>16
    <FILENAME>bmo_sterling-secondamendmei.jpg
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 16 - file: bmo_sterling-secondamendmei.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>17
    <FILENAME>bmo_sterling-secondamendmej.jpg
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 17 - file: bmo_sterling-secondamendmej.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>18
    <FILENAME>bmo_sterling-secondamendmek.jpg
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 18 - file: bmo_sterling-secondamendmek.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>19
    <FILENAME>bmo_sterling-secondamendmel.jpg
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 19 - file: bmo_sterling-secondamendmel.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>20
    <FILENAME>bmo_sterling-secondamendmem.jpg
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 20 - file: bmo_sterling-secondamendmem.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>21
    <FILENAME>bmo_sterling-secondamendmen.jpg
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 21 - file: bmo_sterling-secondamendmen.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>22
    <FILENAME>bmo_sterling-secondamendmeo.jpg
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 22 - file: bmo_sterling-secondamendmeo.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>23
    <FILENAME>bmo_sterling-secondamendmep.jpg
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 23 - file: bmo_sterling-secondamendmep.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>24
    <FILENAME>bmo_sterling-secondamendmeq.jpg
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 24 - file: bmo_sterling-secondamendmeq.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>25
    <FILENAME>bmo_sterling-secondamendmer.jpg
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 25 - file: bmo_sterling-secondamendmer.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>GRAPHIC
    <SEQUENCE>26
    <FILENAME>sterling_logoa03a.jpg
    <DESCRIPTION>GRAPHIC
    <TEXT>
    Document 26 - file: sterling_logoa03a.jpg

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>XML
    <SEQUENCE>27
    <FILENAME>strl-20210628_htm.xml
    <DESCRIPTION>IDEA: XBRL DOCUMENT
    <TEXT>
    Document 27 - file: strl-20210628_htm.html

    Document 27 - RAW XML: strl-20210628_htm.xml

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>XML
    <SEQUENCE>28
    <FILENAME>R1.htm
    <DESCRIPTION>IDEA: XBRL DOCUMENT
    <TEXT>
    Document 28 - file: R1.htm

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>EXCEL
    <SEQUENCE>29
    <FILENAME>Financial_Report.xlsx
    <DESCRIPTION>IDEA: XBRL DOCUMENT
    <TEXT>
    Document 29 - file: Financial_Report.xlsx

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>XML
    <SEQUENCE>30
    <FILENAME>Show.js
    <DESCRIPTION>IDEA: XBRL DOCUMENT
    <TEXT>
    Document 30 - file: Show.js

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>XML
    <SEQUENCE>31
    <FILENAME>report.css
    <DESCRIPTION>IDEA: XBRL DOCUMENT
    <TEXT>
    Document 31 - file: report.css

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>XML
    <SEQUENCE>32
    <FILENAME>FilingSummary.xml
    <DESCRIPTION>IDEA: XBRL DOCUMENT
    <TEXT>
    Document 32 - file: FilingSummary.html

    Document 32 - RAW XML: FilingSummary.xml

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>JSON
    <SEQUENCE>34
    <FILENAME>MetaLinks.json
    <DESCRIPTION>IDEA: XBRL DOCUMENT
    <TEXT>
    Document 34 - file: MetaLinks.json

    </DOCUMENT>
    <DOCUMENT>
    <TYPE>ZIP
    <SEQUENCE>35
    <FILENAME>0000874238-21-000059-xbrl.zip
    <DESCRIPTION>IDEA: XBRL DOCUMENT
    <TEXT>
    Document 35 - file: 0000874238-21-000059-xbrl.zip

    </DOCUMENT>
    </SEC-DOCUMENT>