Acquisitions, Discontinued Operations and Formation of Shanghai Electric JV (Details 2)	3 Months Ended								12 Months Ended				12 Months Ended		3 Months Ended				12 Months Ended															0 Months Ended	1 Months Ended		3 Months Ended	12 Months Ended
	Dec. 31, 2014 USD ($)	Sep. 27, 2014 USD ($)	Jun. 28, 2014 USD ($)	Mar. 29, 2014 USD ($)	Dec. 31, 2013 USD ($)	Sep. 28, 2013 USD ($)	Jun. 29, 2013 USD ($)	Mar. 30, 2013 USD ($)	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)	Dec. 31, 2012 USD ($)	Dec. 30, 2011 Shanghai Electric JV	Dec. 31, 2014 Fenn USD ($)	Dec. 31, 2014 Precision Components USD ($)	Dec. 31, 2014 TPS USD ($)	Sep. 27, 2014 TPS USD ($)	Jun. 28, 2014 TPS USD ($)	Mar. 29, 2014 TPS USD ($)	Dec. 31, 2014 TPS USD ($)	Dec. 31, 2013 Dielectric USD ($)	Dec. 31, 2013 Dielectric Maximum USD ($)	Dec. 31, 2013 Kayex USD ($)	Dec. 31, 2012 Tianyu USD ($)	Dec. 31, 2012 Tianyu CNY	Dec. 31, 2014 Weil McLain Shandong USD ($)	Dec. 31, 2013 Weil McLain Shandong USD ($)	Dec. 31, 2012 Weil McLain Shandong USD ($)	Dec. 31, 2014 SPX Service Solutions ("Service Solutions") USD ($)	Dec. 31, 2013 SPX Service Solutions ("Service Solutions") USD ($)	Dec. 31, 2012 SPX Service Solutions ("Service Solutions") USD ($)	Dec. 31, 2014 Other businesses sold prior to the earliest date presented in the financial statements USD ($)	Dec. 31, 2013 Other businesses sold prior to the earliest date presented in the financial statements USD ($)	Dec. 31, 2012 Other businesses sold prior to the earliest date presented in the financial statements USD ($)	Dec. 30, 2011 Certain assets of dry cooling products business Shanghai Electric JV CNY	Dec. 31, 2012 Certain assets of dry cooling products business Shanghai Electric JV CNY	Jan. 31, 2012 Certain assets of dry cooling products business Shanghai Electric JV CNY	Mar. 31, 2012 Certain assets of dry cooling products business Shanghai Electric JV USD ($)	Dec. 31, 2013 Certain assets of dry cooling products business Shanghai Electric JV CNY
Discontinued Operations
Cash consideration, exclusive of cash transferred									$ 108,600,000	$ 13,500,000	$ 1,133,400,000		$ 3,500,000	$ 62,600,000				$ 42,500,000	$ 42,500,000	$ 4,700,000				1			$ 2,700,000
Gain (loss) on sale of business, net of tax									13,300,000	(4,000,000)	313,400,000		(400,000)	(6,900,000)	200,000	200,000	200,000	21,500,000	21,700,000		100,000	1,300,000	(1,800,000)				2,200,000			313,400,000
Cash consideration, gross																						6,900,000								1,134,900,000				96,700,000	25,800,000	51,500,000		19,400,000
Cash transferred with discontinued business																							1,100,000				3,100,000
Adjustment to gain or loss on sale of discontinued operations, net of tax																									(1,100,000)	(400,000)		2,100,000	(300,000)		(2,100,000)	(4,600,000)	(400,000)
Working capital settlement														400,000												1,100,000			800,000
Income from discontinued operations and related income taxes
Income from discontinued operations									22,100,000	3,600,000	612,700,000
Income tax provision									(13,800,000)	(2,300,000)	(264,300,000)
Income 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
Results of operations for discontinued operations
Revenues									27,700,000	148,900,000	1,030,600,000
Pre-tax income (loss)									(6,100,000)	7,000,000	57,100,000
Assets:
Accounts receivable, net					19,100,000					19,100,000
Inventories, net					33,900,000					33,900,000
Other current assets					1,100,000					1,100,000
Property, plant and equipment, net					12,100,000					12,100,000
Goodwill and intangibles, net					34,700,000					34,700,000
Assets of discontinued operations					100,900,000					100,900,000
Liabilities:
Accounts payable					10,400,000					10,400,000
Accrued expenses					17,000,000					17,000,000
Liabilities of discontinued operations					27,400,000					27,400,000
Other information
Interest acquired in joint venture (as a percent)												45.00%
Net gain associated with deconsolidation																																					$ 20,500,000