Quarterly Results (Unaudited) (Details) (USD $)	3 Months Ended								12 Months Ended
	Dec. 31, 2011	Oct. 01, 2011 D	Jul. 02, 2011 D	Apr. 02, 2011 plan	Dec. 31, 2010	Oct. 02, 2010 D	Jul. 03, 2010 D	Apr. 03, 2010	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Quarterly Results (Unaudited)
Operating revenues	$ 1,263,700,000	$ 1,166,000,000	$ 1,136,800,000	$ 984,900,000	$ 1,115,900,000	$ 1,094,700,000	$ 989,900,000	$ 913,400,000	$ 4,551,400,000	$ 4,113,900,000	$ 4,175,100,000
Gross profit	347,000,000	323,600,000	314,400,000	292,800,000	334,700,000	327,700,000	301,100,000	270,800,000
Income from continuing operations	58,400,000	50,800,000	25,000,000	20,700,000	64,400,000	35,000,000	64,600,000	14,000,000	154,900,000	178,000,000	224,200,000
Income (loss) from discontinued operation, net of tax	5,100,000	11,500,000	10,000,000	4,100,000	(600,000)	4,700,000	13,400,000	7,300,000	30,700,000	24,800,000	(208,000,000)
Net income	63,500,000	62,300,000	35,000,000	24,800,000	63,800,000	39,700,000	78,000,000	21,300,000	185,600,000	202,800,000	16,200,000
Less: Net income (loss) attributable to noncontrolling interests	1,000,000	1,600,000	700,000	1,700,000	(1,500,000)	300,000	(800,000)	(800,000)	5,000,000	(2,800,000)	(15,500,000)
Net income attributable to SPX Corporation common shareholders	62,500,000	60,700,000	34,300,000	23,100,000	65,300,000	39,400,000	78,800,000	22,100,000	180,600,000	205,600,000	31,700,000
Basic earnings (loss) per share of common stock:
Continuing operations (in dollars per share)	$ 1.14	$ 0.97	$ 0.48	$ 0.38	$ 1.32	$ 0.70	$ 1.32	$ 0.30	$ 2.97	$ 3.64	$ 4.50
Discontinued operations, net of tax (in dollars per share)	$ 0.10	$ 0.23	$ 0.20	$ 0.08	$ (0.01)	$ 0.09	$ 0.27	$ 0.15	$ 0.61	$ 0.50	$ (3.86)
Net income (in dollars per share)	$ 1.24	$ 1.20	$ 0.68	$ 0.46	$ 1.31	$ 0.79	$ 1.59	$ 0.45	$ 3.58	$ 4.14	$ 0.64
Diluted earnings (loss) per share of common stock:
Continuing operations (in dollars per share)	$ 1.13	$ 0.97	$ 0.47	$ 0.37	$ 1.30	$ 0.69	$ 1.30	$ 0.29	$ 2.94	$ 3.59	$ 4.47
Discontinued operations, net of tax (in dollars per share)	$ 0.10	$ 0.23	$ 0.20	$ 0.08	$ (0.01)	$ 0.09	$ 0.27	$ 0.15	$ 0.60	$ 0.49	$ (3.83)
Net income per share attributable to SPX Corporation common shareholders (in dollars per share)	$ 1.23	$ 1.20	$ 0.67	$ 0.45	$ 1.29	$ 0.78	$ 1.57	$ 0.44	$ 3.54	$ 4.08	$ 0.64
Charges associated with restructuring initiatives	11,400,000	7,200,000	4,300,000	2,400,000	15,200,000	7,500,000	3,900,000	4,100,000
Income (expense) for foreign currency transactions and FX forward contracts and FX embedded derivatives	(4,800,000)	(30,900,000)	(3,500,000)	(2,200,000)	(4,900,000)	(6,900,000)	(2,900,000)	(12,800,000)
Impairment charges	3,600,000		24,700,000						28,300,000	1,700,000	6,100,000
Number of domestic pension plans amortized				1
Reduction in pension expense for each quarter	5,000,000	5,000,000	5,000,000	5,000,000
Tax credits related to expansion of power transformer facility in Waukesha, WI	4,000,000	2,000,000	900,000	800,000					7,700,000
Income tax benefit associated with the release of the valuation allowance on existing foreign tax credit carryforwards		27,800,000							27,800,000
Federal income taxes recorded in connection with plan to repatriate a portion of the earnings of a foreign subsidiary		6,900,000							6,900,000
Charge resulting from insolvency of insurance carrier for certain risk management matters	19,400,000
Charge associated with amounts that are deemed uncollectible from an insolvent insurer, portion recorded in other expense, net	18,200,000
Charge associated with amounts that are deemed uncollectible from an insolvent insurer, portion recorded in discontinued operations, net of tax	1,200,000
Decrease in incentive compensation expense for the fourth quarter of 2011 related to the fourth quarter of 2010	13,300,000
Domestic charge for the taxation of prescription drug costs for retirees that partially offset benefits								6,200,000		6,200,000
Income tax benefit resulting from settlement with taxing authority recorded in continuing operations							22,000,000			18,200,000
Income tax benefit resulting from settlement with taxing authority recorded in discontinued operations							7,300,000	(3,800,000)		7,300,000
Favorable impact effective income tax rate related to uncertain tax positions					16,000,000					16,000,000
Repatriation of foreign earnings that partially offset benefits					3,600,000					3,600,000
Number of days in the quarter		91	91			91	91
Sale of discontinued operations
Tax benefits associated with the conclusion of a Canadian appeals process			2,500,000						2,500,000
Industrial Products and Services
Quarterly Results (Unaudited)
Operating revenues									865,200,000	849,600,000	945,500,000
Sale of discontinued operations
Insurance recovery related to a product liability matter				6,300,000
Thermal Equipment and Services reportable segment
Quarterly Results (Unaudited)
Operating revenues									1,644,200,000	1,602,100,000	1,595,500,000
Sale of discontinued operations
Net charges associated with changes in cost estimates for certain contracts in South Africa	10,700,000
Clyde Union
Sale of discontinued operations
Charges associated with FX forward contracts used to hedge the acquisition purchase price	4,000,000	30,600,000
PSD Inc.
Sale of discontinued operations
Cash consideration received in sale of discontinued operation								3,000,000
Gain on sale, net of taxes								$ 3,600,000