SHAREHOLDERS' EQUITY AND STOCK-BASED COMPENSATION (Details 3) - USD ($) $ in Millions	3 Months Ended					9 Months Ended		12 Months Ended
	Sep. 26, 2015	Jun. 27, 2015	Sep. 27, 2014	Jun. 28, 2014	Mar. 29, 2014	Sep. 26, 2015	Sep. 27, 2014	Dec. 31, 2014	Dec. 31, 2013
Components of accumulated other comprehensive income (loss)
Balance at beginning of year						$ 62.6
Balance at end of period	$ 286.6					286.6		$ 62.6
Pension and postretirement liability adjustment and other, tax (provision) benefit	(0.3)					(0.2)	$ (2.3)
Discontinued Operations, Disposed of by Means Other than Sale, Spinoff | SPX Flow, Inc
Components of accumulated other comprehensive income (loss)
Current-period other comprehensive income (loss)	354.6					354.6
Accumulated Other Comprehensive Income (Loss)
Components of accumulated other comprehensive income (loss)
Balance at beginning of year	(27.2)		$ 284.7		$ 287.5	62.6	287.5	287.5
Other comprehensive income (loss) before reclassifications	(41.5)		(115.8)			(130.8)	(123.8)
Amounts reclassified from accumulated other comprehensive loss	0.7		0.1			0.2	5.3
Current-period other comprehensive income (loss)	(40.8)		(115.7)			(130.6)	(118.5)
Balance at end of period	286.6	$ (27.2)	169.0	$ 284.7		286.6	169.0	62.6	$ 287.5
Foreign Currency Translation Adjustment
Components of accumulated other comprehensive income (loss)
Balance at beginning of year	(30.4)		285.3		296.8	59.0	296.8	296.8
Other comprehensive income (loss) before reclassifications	(41.5)		(115.3)			(130.9)	(126.8)
Amounts reclassified from accumulated other comprehensive loss	0.0		0.0			0.0	0.0
Current-period other comprehensive income (loss)	(41.5)		(115.3)			(130.9)	(126.8)
Balance at end of period	282.6	(30.4)	170.0	285.3		282.6	170.0	59.0	296.8
Foreign Currency Translation Adjustment | Discontinued Operations, Disposed of by Means Other than Sale, Spinoff | SPX Flow, Inc
Components of accumulated other comprehensive income (loss)
Current-period other comprehensive income (loss)	354.5					354.5
Net Unrealized Gains (Losses) on Qualifying Cash Flow Hedges
Components of accumulated other comprehensive income (loss)
Balance at beginning of year	(1.4)		(0.9)		(0.8)	(1.3)	(0.8)	(0.8)
Other comprehensive income (loss) before reclassifications	(0.5)		(0.5)			(0.4)	(0.8)
Amounts reclassified from accumulated other comprehensive loss	0.8		0.2			0.6	0.4
Current-period other comprehensive income (loss)	0.3		(0.3)			0.2	(0.4)
Balance at end of period	(1.0)	(1.4)	(1.2)	(0.9)		(1.0)	(1.2)	(1.3)	(0.8)
Net unrealized gain (loss) on qualifying cash flow hedges, tax benefit (provision)	0.8	0.4	1.0	0.9		0.8	1.0	1.1	1.0
Net Unrealized Gains (Losses) on Qualifying Cash Flow Hedges | Discontinued Operations, Disposed of by Means Other than Sale, Spinoff | SPX Flow, Inc
Components of accumulated other comprehensive income (loss)
Current-period other comprehensive income (loss)	0.1					0.1
Net Unrealized Losses on Available-for-Sale Securities
Components of accumulated other comprehensive income (loss)
Balance at beginning of year					(3.7)		(3.7)	(3.7)
Other comprehensive income (loss) before reclassifications							3.6
Amounts reclassified from accumulated other comprehensive loss							0.1
Current-period other comprehensive income (loss)							3.7
Balance at end of period			0.0				0.0		(3.7)
Pension and Postretirement Liability Adjustment
Components of accumulated other comprehensive income (loss)
Balance at beginning of year	4.6		0.3		(4.8)	4.9	(4.8)	(4.8)
Other comprehensive income (loss) before reclassifications	0.5		0.0			0.5	0.2
Amounts reclassified from accumulated other comprehensive loss	(0.1)		(0.1)			(0.4)	4.8
Current-period other comprehensive income (loss)	0.4		(0.1)			0.1	5.0
Balance at end of period	5.0	4.6	0.2	$ 0.3		5.0	0.2	4.9	(4.8)
Pension and postretirement liability adjustment and other, tax (provision) benefit	3.2	$ 2.9	$ 0.1		$ 0.1	3.2	$ 0.1	$ 3.0	(2.2)
Pension and Postretirement Liability Adjustment | EGS Electrical Group, LLC and Subsidiaries ("EGS")
Components of accumulated other comprehensive income (loss)
Pension and postretirement liability adjustment and other, tax (provision) benefit									$ 5.0
Pension and Postretirement Liability Adjustment | Discontinued Operations, Disposed of by Means Other than Sale, Spinoff | SPX Flow, Inc
Components of accumulated other comprehensive income (loss)
Current-period other comprehensive income (loss)	$ 0.0					$ 0.0