Significant Accounting Policies (Details)	12 Months Ended
Dec. 31, 2017
Significant Accounting Policies [Abstract]
Percentage of tuition revenue in total revenue	96.00%
Unused books and academic material refundable period	21 days

The period to return unused books and related academic materials in order to receive a full refund.

No definition available.

Name:	stra_UnusedBooksAndAcademicMaterialRefundablePeriod
Namespace Prefix:	stra_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration