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v3.20.4

Significant Accounting Policies - Deferred Costs (Details) | 12 Months Ended
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Dec. 31, 2020
Minimum |
Accounting Policies [Line Items] |
Amortization period of deferred costs | 1 year
Maximum |
Accounting Policies [Line Items] |
Amortization period of deferred costs | 2 years

X
- Definition [Line Items] for Accounting Policies [Table] + References No definition available. + Details
Name: | stra_AccountingPoliciesLineItems
Namespace Prefix: | stra_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Deferred Charges, Amortization Period + References No definition available. + Details
Name: | stra_DeferredChargesAmortizationPeriod
Namespace Prefix: | stra_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | srt_RangeAxis=srt_MinimumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_RangeAxis=srt_MaximumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |