Quarterly Results (Unaudited) (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 29, 2012 D	Jun. 30, 2012 D	Mar. 31, 2012	Dec. 31, 2011	Oct. 01, 2011	Jul. 02, 2011	Apr. 02, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Quarterly Results (Unaudited)
Operating revenues	$ 1,435.7	$ 1,242.7	$ 1,258.1	$ 1,163.7	$ 1,258.1	$ 1,162.7	$ 1,134.2	$ 981.9	$ 5,100.2	$ 4,536.9	$ 4,098.8
Gross profit	402.5	335.1	336.5	300.9	345.9	322.9	313.9	292.0
Income (loss) from continuing operations	(179.2)	54.1	38.5	8.2	58.5	50.8	25.5	20.8	(78.4)	155.6	178.0
Income from discontinued operation, net of tax	320.0	6.1	9.7	4.6	5.0	11.5	9.5	4.0	340.4	30.0	24.8
Net income	140.8	60.2	48.2	12.8	63.5	62.3	35.0	24.8	262.0	185.6	202.8
Less: Net income (loss) attributable to noncontrolling interests	0.3	2.4	0.8	(0.7)	1.0	1.6	0.7	1.7	2.8	5.0	(2.8)
Net income attributable to SPX Corporation common shareholders	140.5	57.8	47.4	13.5	62.5	60.7	34.3	23.1
Basic earnings per share of common stock:
Continuing operations (in dollars per share)	$ (3.62)	$ 1.03	$ 0.75	$ 0.18	$ 1.14	$ 0.97	$ 0.49	$ 0.38	$ (1.62)	$ 2.98	$ 3.64
Discontinued operations, net of tax (in dollars per share)	$ 6.45	$ 0.13	$ 0.20	$ 0.09	$ 0.10	$ 0.23	$ 0.19	$ 0.08	$ 6.80	$ 0.60	$ 0.50
Net income (in dollars per share)	$ 2.83	$ 1.16	$ 0.95	$ 0.27	$ 1.24	$ 1.20	$ 0.68	$ 0.46	$ 5.18	$ 3.58	$ 4.14
Diluted earnings per share of common stock:
Continuing operations (in dollars per share)	$ (3.62)	$ 1.03	$ 0.74	$ 0.17	$ 1.13	$ 0.97	$ 0.48	$ 0.37	$ (1.62)	$ 2.96	$ 3.59
Discontinued operations, net of tax (in dollars per share)	$ 6.45	$ 0.13	$ 0.19	$ 0.09	$ 0.10	$ 0.22	$ 0.19	$ 0.08	$ 6.80	$ 0.58	$ 0.49
Net income per share attributable to SPX Corporation common shareholders (in dollars per share)	$ 2.83	$ 1.16	$ 0.93	$ 0.26	$ 1.23	$ 1.19	$ 0.67	$ 0.45	$ 5.18	$ 3.54	$ 4.08
Charges associated with restructuring initiatives	6.2	7.1	8.4	2.4	11.5	7.2	4.2	2.4
Income (expense) for foreign currency transactions and FX forward contracts and FX embedded derivatives	(2.1)	(3.2)	(1.9)	(5.2)	(4.8)	(30.9)	(3.5)	(2.2)
Impairment charges							24.7		285.9	28.3	1.7
Income tax charges related to valuation allowances recorded against deferred income tax assets	6.3								5.4
Income tax charges related to foreign dividends and undistributed foreign earnings that are no longer considered to be indefinitely reinvested	15.4								15.4
Increase in incentive compensation expense for the fourth quarter of 2012 related to the fourth quarter of 2011	20.6
Tax credits related to expansion of power transformer facility in Waukesha, WI					4.0	2.0	0.9	0.8		7.7
Pre-tax gain on deconsolidation of dry cooling business				20.5					20.5
Incremental income tax charge				6.1					6.1
Tax benefit related to audit settlements and statute expirations	21.0								23.7
Income tax benefit associated with the release of the valuation allowance on existing foreign tax credit carryforwards						27.8				27.8
Goodwill impairments	(270.4)								(270.4)	(20.8)
Federal income taxes recorded in connection with plan to repatriate a portion of the earnings of a foreign subsidiary						6.9				6.9
Charge resulting from insolvency of insurance carrier for certain risk management matters					19.4
Charge associated with amounts that are deemed uncollectible from an insolvent insurer, portion recorded in other expense, net					18.2
Charge associated with amounts that are deemed uncollectible from an insolvent insurer, portion recorded in discontinued operations, net of tax					1.2
Number of days in the quarter		91	91
Sale of discontinued operations
Impairment charges									(281.4)
Gain on disposition of discontinued operations, net of tax									313.4	0.3	11.7
SPX Heat Transfer Inc.
Diluted earnings per share of common stock:
Impairment charges					3.6		24.7
Goodwill impairments					(3.6)		(17.2)			(20.8)
Industrial Products and Services
Quarterly Results (Unaudited)
Operating revenues									927.1	858.5	843.4
Sale of discontinued operations
Insurance recovery related to a product liability matter								6.3
Impairment charges										(0.8)
Thermal Equipment and Services reportable segment
Quarterly Results (Unaudited)
Operating revenues									1,490.9	1,636.4	1,593.2
Diluted earnings per share of common stock:
Impairment charges										4.5
Goodwill impairments									(270.4)	(20.8)
Sale of discontinued operations
Net charges associated with changes in cost estimates for certain contracts in South Africa					10.7
Impairment charges									(4.5)	(7.5)
Cooling
Diluted earnings per share of common stock:
Impairment charges	281.4								281.4
Goodwill impairments	(270.4)								(270.4)
Sale of discontinued operations
Impairment charges	(11.0)								(11.0)
Income tax benefit associated with the impairment charges									26.3
Clyde Union
Sale of discontinued operations
Charges associated with FX forward contracts used to hedge the acquisition purchase price					4.0	30.6
SPX Service Solutions ("Service Solutions")
Sale of discontinued operations
Gain on disposition of discontinued operations, net of tax	$ 313.4