Represents the amount of shares sold as part of a block in a forward sales agreement.

No definition available.

Name:	sr_ForwardSalesAgreementsBlockSalesShares
Namespace Prefix:	sr_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

Note 4 - Shareholders' Equity (Details Textual) - At The Market Program [Member] - USD ($) $ in Millions	Dec. 11, 2023	Jan. 25, 2024	Dec. 31, 2023
Forward Sales Agreements, Block Sales, Shares (in shares)	1,744,549
Forward Sales Agreements, Proceeds If Settled			$ 112.2
Subsequent Event [Member]
Sale of Stock, Maximum Aggregate Offering Price		$ 200.0