Acquisitions - 2016, Allocation (Details) - USD ($) $ in Millions		3 Months Ended	12 Months Ended
	Nov. 17, 2016	Dec. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Allocation of Consideration Transferred:
Goodwill		$ 130.6	$ 169.8	$ 130.6	$ 130.6	$ 127.8
Bargain purchase gain			$ (0.6)	(9.2)
2016 Acquisitions
Consideration Transferred:
Cash paid				25.9
Cash acquired				(1.6)
Shares issued				2.0
Contingent consideration				5.1
Total consideration transferred				31.4
Allocation of Consideration Transferred:
Accounts receivable		6.9		6.9
Inventories		19.1		19.1
Other current assets		0.1		0.1
Property, plant and equipment		7.5		7.5
Goodwill		1.0		1.0
Bargain purchase gain				(9.2)
Deferred taxes, net		(1.0)		(1.0)
Liabilities assumed		(10.2)		(10.2)
Total consideration transferred		31.4		$ 31.4
2016 Acquisitions | Maximum
Allocation of Consideration Transferred:
Amortization period for intangible assets acquired				7 years
2016 Acquisitions | Minimum
Allocation of Consideration Transferred:
Amortization period for intangible assets acquired				5 years
Oxford Instruments Superconducting Wire LLC
Consideration Transferred:
Total consideration transferred	$ 15.9
Allocation of Consideration Transferred:
Bargain purchase gain		(9.2)		$ (9.2)
Customer relationships | 2016 Acquisitions
Allocation of Consideration Transferred:
Intangible assets		2.0		2.0
Existing technology | 2016 Acquisitions
Allocation of Consideration Transferred:
Intangible assets		14.6		14.6
Trade names | 2016 Acquisitions
Allocation of Consideration Transferred:
Intangible assets		$ 0.6		$ 0.6