Special Charges, Net - Analysis of Restructuring Liabilities (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 30, 2024	Apr. 01, 2023
Restructuring liabilities
Balance at beginning of year	$ 0.7	$ 0.0
Special charges	0.6	0.0
Utilization — cash	(0.4)	0.0
Currency translation adjustment and other	(0.1)	0.0
Balance at end of period	$ 0.8	$ 0.0

Reserve increase representing the amount charged against earnings in the period for a specified incurred and estimated type of cost associated with exit from or disposal of business activities or restructuring pursuant to a duly authorized plan. Also includes the amount charged against earnings in the period for integration expenses.

No definition available.

Name:	spxc_RestructuringAndIntegrationReservesPeriodExpense
Namespace Prefix:	spxc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration