ACQUISITION, DISCONTINUED OPERATIONS AND FORMATION OF SHANGHAI ELECTRIC JV (Details 2)	3 Months Ended		9 Months Ended					3 Months Ended											9 Months Ended	3 Months Ended		9 Months Ended		0 Months Ended	1 Months Ended			3 Months Ended
	Sep. 28, 2013 USD ($)	Sep. 29, 2012 USD ($)	Sep. 28, 2013 USD ($)	Sep. 29, 2012 USD ($)	Dec. 31, 2012 USD ($)	Sep. 28, 2013 Shanghai Electric JV	Dec. 30, 2011 Shanghai Electric JV	Jun. 29, 2013 Dielectric USD ($)	Jun. 29, 2013 Dielectric Maximum USD ($)	Sep. 28, 2013 Kayex USD ($)	Mar. 30, 2013 Kayex USD ($)	Dec. 31, 2012 Tianyu USD ($)	Dec. 31, 2012 Tianyu CNY	Jun. 29, 2013 Weil McLain Shandong USD ($)	Mar. 30, 2013 Weil McLain Shandong USD ($)	Dec. 31, 2012 Weil McLain Shandong USD ($)	Sep. 28, 2013 SPX Service Solutions ("Service Solutions") USD ($)	Dec. 31, 2012 SPX Service Solutions ("Service Solutions") USD ($)	Sep. 28, 2013 SPX Service Solutions ("Service Solutions") USD ($)	Sep. 28, 2013 Other businesses sold prior to the earliest date presented in the financial statements USD ($)	Sep. 29, 2012 Other businesses sold prior to the earliest date presented in the financial statements USD ($)	Sep. 28, 2013 Other businesses sold prior to the earliest date presented in the financial statements USD ($)	Sep. 29, 2012 Other businesses sold prior to the earliest date presented in the financial statements USD ($)	Dec. 30, 2011 Certain assets of dry cooling products business Shanghai Electric JV CNY	Jul. 31, 2013 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 ($)
Discontinued Operations
Gain (loss) on sale of business, net of tax	$ 200,000	$ (700,000)	$ (2,300,000)	$ (1,600,000)					$ 100,000	$ 3,600,000	$ (2,100,000)	$ (1,800,000)				$ 2,200,000		$ 313,400,000
Cash consideration, exclusive of cash transferred								4,700,000					1			2,700,000
Cash consideration, gross										6,900,000								1,134,900,000							19,400,000	25,800,000	51,500,000
Cash transferred with discontinued business												1,100,000				3,100,000
Adjustment to gain (loss) on sale of discontinued operations, net of tax															(400,000)		(3,100,000)		(1,500,000)	(300,000)	(700,000)	(1,900,000)	(1,600,000)
Working capital settlement														1,100,000			800,000
Income from discontinued operations and related income taxes
Income from discontinued operations	8,700,000	17,700,000	12,200,000	57,700,000
Income tax provision	(3,600,000)	(6,000,000)	(4,300,000)	(19,700,000)
Income from discontinued operations, net of tax	5,100,000	11,700,000	7,900,000	38,000,000
Results of operations for businesses reported as discontinued operations
Revenues	50,700,000	269,600,000	154,200,000	877,800,000
Pre-tax income	8,300,000	18,800,000	15,000,000	60,500,000
Assets:
Accounts receivable, net	28,400,000		28,400,000		21,200,000
Inventories, net	40,900,000		40,900,000		32,700,000
Other current assets	1,100,000		1,100,000		1,200,000
Property, plant and equipment, net	16,800,000		16,800,000		16,200,000
Goodwill and intangibles, net	70,600,000		70,600,000		71,300,000
Assets of discontinued operations	157,800,000		157,800,000		142,600,000
Liabilities:
Accounts payable	17,100,000		17,100,000		18,300,000
Accrued expenses	14,400,000		14,400,000		16,600,000
Liabilities of discontinued operations	31,500,000		31,500,000		34,900,000
Other information
Interest acquired in joint venture (as a percent)						45.00%	45.00%
Dispositions, consideration to be received																								96,700,000
Net gain associated with deconsolidation				$ 20,500,000																								$ 20,500,000