SHAREHOLDERS' EQUITY AND STOCK-BASED COMPENSATION (Details 8) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 28, 2015	Mar. 29, 2014
Changes in Equity
Balance	$ 1,821.1	$ 2,172.0
Net income (loss)	(10.0)	317.8
Net unrealized gains (losses) on qualifying cash flow hedges, net of tax (provision) benefit of $(0.6) and $0.2 for the three months ended March 28, 2015 and March 29, 2014, respectively	0.7	(0.7)
Net unrealized gains (losses) on qualifying cash flow hedges, tax (provision) benefit	(0.6)	0.2
Net unrealized gains on available-for-sale securities		3.5
Pension liability adjustment, net of tax provision of $2.3 for the three months ended March 29, 2014	(0.2)	5.2
Pension liability adjustment, tax provision		2.3
Foreign currency translation adjustments	(131.0)	(2.1)
Total comprehensive income (loss), net	(140.5)	323.7
Dividends declared	(15.4)	(16.3)
Incentive plan activity	4.9	4.8
Stock-based compensation expense	23.6	24.7
Restricted stock and restricted stock unit vesting, net of tax withholdings, and related tax benefit of $0.4 and $8.8 for the three months ended March 28, 2015 and March 29, 2014, respectively	(5.5)	(11.5)
Restricted stock and restricted stock unit vesting, net of tax withholdings, tax benefit	0.4	8.8
Common stock repurchases		(134.3)
Dividends attributable to noncontrolling interests	(0.5)
Balance	1,687.7	2,363.1
SPX Corporation Shareholders' Equity
Changes in Equity
Balance	1,817.9	2,158.0
Net income (loss)	(7.1)	318.2
Net unrealized gains (losses) on qualifying cash flow hedges, net of tax (provision) benefit of $(0.6) and $0.2 for the three months ended March 28, 2015 and March 29, 2014, respectively	0.7	(0.7)
Net unrealized gains on available-for-sale securities		3.5
Pension liability adjustment, net of tax provision of $2.3 for the three months ended March 29, 2014	(0.2)	5.2
Foreign currency translation adjustments	(131.1)	(2.0)
Total comprehensive income (loss), net	(137.7)	324.2
Dividends declared	(15.4)	(16.3)
Incentive plan activity	4.9	4.8
Stock-based compensation expense	23.6	24.7
Restricted stock and restricted stock unit vesting, net of tax withholdings, and related tax benefit of $0.4 and $8.8 for the three months ended March 28, 2015 and March 29, 2014, respectively	(5.5)	(11.5)
Common stock repurchases		(134.3)
Balance	1,687.8	2,349.6
Noncontrolling Interests
Changes in Equity
Balance	3.2	14.0
Net income (loss)	(2.9)	(0.4)
Foreign currency translation adjustments	0.1	(0.1)
Total comprehensive income (loss), net	(2.8)	(0.5)
Dividends attributable to noncontrolling interests	(0.5)
Balance	$ (0.1)	$ 13.5