SPECIAL CHARGES, NET - Special Charges (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Oct. 01, 2022	Oct. 02, 2021	Oct. 01, 2022	Oct. 02, 2021
Special Charges, Net
Special charges	$ 0.0	$ (0.1)	$ 0.1	$ 0.7
Operating Segments \| HVAC reportable segment
Special Charges, Net
Special charges	0.0	(0.1)	0.1	0.1
Operating Segments \| Detection and Measurement reportable segment
Special Charges, Net
Special charges	$ 0.0	$ 0.0	$ 0.0	$ 0.6

Amount charged against earnings in the period for incurred and estimated costs associated with an exit from business activities or restructuring pursuant to a duly authorized plan, excluding asset retirement obligations. Such costs include charges associated with employee terminations, lease terminations, asset impairments, etc.

No definition available.

Name:	spxc_SpecialCharges
Namespace Prefix:	spxc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration