Inventories (Schedule of Inventories) (Details) - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Inventory, Net [Abstract]
Separative work units inventory	$ 53.9	$ 47.2
Uranium inventory	110.1	105.9
Inventories	164.0	153.1
Separative work units owed to customers and suppliers	23.3	15.0
Uranium owed to customers and suppliers	70.5	62.9
Inventories owed to customers and suppliers	93.8	77.9
Separative work units net of liability	30.6	32.2
Uranium inventory net of liability	39.6	43.0
Inventories, net	$ 70.2	$ 75.2

Amount after valuation and LIFO reserves of inventory expected to be sold, or consumed within one year or operating cycle, if longer.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.6(a))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 330
-SubTopic 10
-Section 35
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=68049868&loc=d3e3927-108312

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section 45
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=82887183&loc=d3e6676-107765

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