Business Segment Information (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014 segment	Sep. 30, 2013	Dec. 31, 2013
Business Segment Information
Number of reporting segments			2
Revenue:
Total revenue	$ 419.8	$ 439.0	$ 1,300.9	$ 1,287.3
Operating Income:
Total operating income	4.9	31.5	60.9	87.2
Assets:
Total assets	1,910.6		1,910.6		1,988.3
Eliminations
Revenue:
Total revenue	(3.6)	(4.1)	(14.1)	(12.0)
Corporate, eliminations and other
Operating Income:
Total operating income	0.2	(1.5)	1.3	(3.5)
Assets:
Total assets	(61.4)		(61.4)		(83.5)
BSI | Operating segments
Revenue:
Total revenue	383.4	410.6	1,198.8	1,198.5
Operating Income:
Total operating income	0.8	33.8	48.5	84.0
Assets:
Total assets	1,864.9		1,864.9		1,925.3
Energy and Supercon Technologies | Operating segments
Revenue:
Total revenue	40.0	32.5	116.2	100.8
Operating Income:
Total operating income	3.9	(0.8)	11.1	6.7
Assets:
Total assets	$ 107.1		$ 107.1		$ 146.5