Segment Information Segment Information (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2016	Dec. 31, 2015
Segment Reporting [Abstract]
Revenue from top 10 customers	90.00%
Revenue from top 4 customers	50.00%
Revenue from first customer over 10 percent	15.00%	25.00%
Revenue from second customer over 10 percent	12.00%	13.00%
Revenue from third customer over 10 percent	12.00%	15.00%
Revenue from fourth customer over 10 percent	11.00%	10.00%
Assets LEU segment	$ 686.0	$ 795.3
Assets contract services segment	27.5	24.8
Assets	$ 713.5	$ 820.1

Sum of the carrying amounts as of the balance sheet date of all assets that are recognized. Assets are probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(12))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(11))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Name:	us-gaap_Assets
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant