Segment Reporting - Additional Information (Details)	9 Months Ended
Sep. 30, 2019 segment
Segment Reporting [Abstract]
Number of operating segments that meet threshold to qualify as reportable segments	2

Represents the number of operating segments that meet the quantitative thresholds to qualify as reportable segments.

No definition available.

Name:	stra_NumberOfOperatingSegmentsThatMeetThresholdToQualifyAsReportableSegments
Namespace Prefix:	stra_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration