Quarterly Results (Unaudited) (Details) (USD $)	3 Months Ended									12 Months Ended			0 Months Ended
	Dec. 31, 2014	Dec. 31, 2014	Sep. 27, 2014	Jun. 28, 2014	Mar. 29, 2014	Dec. 31, 2013	Sep. 28, 2013	Jun. 29, 2013	Mar. 30, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Jan. 07, 2014	Feb. 11, 2014	Dec. 31, 2007
Quarterly Results (Unaudited)
Operating revenues		$ 1,277,700,000	$ 1,171,200,000	$ 1,195,100,000	$ 1,077,100,000	$ 1,328,900,000	$ 1,162,700,000	$ 1,180,900,000	$ 1,100,800,000	$ 4,721,100,000	$ 4,773,300,000	$ 4,894,600,000
Gross profit		367,500,000	347,400,000	347,200,000	301,500,000	401,200,000	344,000,000	338,500,000	297,300,000
Income (loss) from continuing operations, net of tax		(40,000,000)	66,700,000	56,700,000	296,700,000	85,100,000	66,600,000	43,500,000	16,100,000	380,100,000	211,300,000	(165,200,000)
Income (loss) from discontinued operations, net of tax		(3,200,000)	(2,900,000)	(6,700,000)	21,100,000	1,800,000	1,900,000	3,700,000	(6,100,000)	8,300,000	1,300,000	348,400,000
Net income		(43,200,000)	63,800,000	50,000,000	317,800,000	86,900,000	68,500,000	47,200,000	10,000,000	388,400,000	212,600,000	183,200,000
Less: Net income (loss) attributable to noncontrolling interests		(8,200,000)	300,000	(1,200,000)	(400,000)	(100,000)	(800,000)	2,000,000	1,300,000	(9,500,000)	2,400,000	2,800,000
Net income attributable to SPX Corporation common shareholders		(35,000,000)	63,500,000	51,200,000	318,200,000	87,000,000	69,300,000	45,200,000	8,700,000	397,900,000	210,200,000	180,400,000
Basic income (loss) per share of common stock:
Continuing operations (in dollars per share)		$ (0.78)	$ 1.59	$ 1.34	$ 6.72	$ 1.90	$ 1.51	$ 0.91	$ 0.32	$ 9.19	$ 4.61	$ (3.36)
Discontinued operations, net of tax (in dollars per share)		$ (0.08)	$ (0.07)	$ (0.15)	$ 0.47	$ 0.04	$ 0.04	$ 0.08	$ (0.13)	$ 0.19	$ 0.02	$ 6.97
Net income per share attributable to SPX Corporation common shareholders (in dollars per share)		$ (0.86)	$ 1.52	$ 1.19	$ 7.19	$ 1.94	$ 1.55	$ 0.99	$ 0.19	$ 9.38	$ 4.63	$ 3.61
Diluted income (loss) per share of common stock:
Continuing operations (in dollars per share)		$ (0.78)	$ 1.57	$ 1.32	$ 6.59	$ 1.87	$ 1.50	$ 0.90	$ 0.32	$ 9.05	$ 4.55	$ (3.36)
Discontinued operations, net of tax (in dollars per share)		$ (0.08)	$ (0.07)	$ (0.15)	$ 0.47	$ 0.04	$ 0.04	$ 0.08	$ (0.14)	$ 0.20	$ 0.02	$ 6.97
Net income per share attributable to SPX Corporation common shareholders (in dollars per share)		$ (0.86)	$ 1.50	$ 1.17	$ 7.06	$ 1.91	$ 1.54	$ 0.98	$ 0.18	$ 9.25	$ 4.57	$ 3.61
Other Information Related to Quarterly Results
Loss on early extinguishment of debt										(32,500,000)
Pension liability adjustment, tax (provision) benefit										(5,200,000)	1,000,000	800,000
Income taxes	29,700,000									214,100,000	60,300,000	(14,200,000)
Income taxes on repatriation of earnings	18,600,000									18,600,000
Foreign income taxes on restructuring	6,000,000									6,000,000
Valuation allowance on foreign deferred income tax assets	5,100,000	5,100,000								5,100,000
Deferred tax liabilities reduction due to audit settlements and statute expirations	18,300,000
Cash consideration, exclusive of cash transferred										108,600,000	13,500,000	1,133,400,000
Gain (loss) on sale of business, net of tax										13,300,000	(4,000,000)	313,400,000
Number of days in the quarter			91 days	91 days			91 days	91 days
South Africa
Quarterly Results (Unaudited)
Operating revenues										137,300,000	266,300,000	322,400,000
7.625% senior notes
Other Information Related to Quarterly Results
Interest rate percentage					7.625%	7.625%					7.625%			7.625%	7.625%
Loss on early extinguishment of debt					(32,500,000)
EGS Electrical Group, LLC and Subsidiaries ("EGS")
Other Information Related to Quarterly Results
Percentage of interest held in joint venture					44.50%	44.50%					44.50%		44.50%
Proceeds from sale of interest in joint venture					574,100,000								574,100,000
Gain on sale of interest in joint venture					491,200,000					491,200,000
Discontinued operations
Other Information Related to Quarterly Results
Income taxes											(500,000)
TPS
Other Information Related to Quarterly Results
Cash consideration, exclusive of cash transferred					42,500,000					42,500,000
Gain (loss) on sale of business, net of tax		200,000	200,000	200,000	21,500,000					21,700,000
Flow Technology Reportable Segment
Quarterly Results (Unaudited)
Operating revenues										2,596,100,000	2,638,000,000	2,682,200,000
Flow Technology Reportable Segment | Trademarks
Other Information Related to Quarterly Results
Impairment charges		11,700,000				4,700,000					6,700,000
Flow Technology and Thermal Equipment and Services | Trademarks
Other Information Related to Quarterly Results
Impairment charges		20,100,000								20,100,000	6,700,000
Thermal Equipment and Services reportable segment
Quarterly Results (Unaudited)
Operating revenues										1,329,900,000	1,344,200,000	1,490,900,000
Thermal Equipment and Services reportable segment | South Africa
Other Information Related to Quarterly Results
Number of power projects										2
Reduction in revenue and segment income		25,000,000		8,300,000						33,300,000
Thermal Equipment and Services reportable segment | Trademarks
Other Information Related to Quarterly Results
Impairment charges		8,400,000										4,500,000
Cooling
Other Information Related to Quarterly Results
Impairment charges		18,000,000								18,000,000		11,000,000
Pension and postretirement benefit plans
Other Information Related to Quarterly Results
Pre-tax loss related to settlement charge					15,300,000
Gains (losses) related to changes in the fair value of plan assets and actuarial gains (losses)	(86,300,000)	(86,300,000)				800,000				(86,300,000)	800,000
Pension liability adjustment, tax (provision) benefit		$ 27,200,000				$ (1,700,000)