Inventories (Schedule of Inventories) (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Inventory, Net [Abstract]
Separative work units inventory	$ 17.0	$ 7.8
Uranium inventory	47.8	56.7
Inventories	64.8	64.5
Separative work units owed to customers and suppliers	4.6	0.0
Uranium owed to customers and suppliers	0.3	5.6
Inventories owed to customers and suppliers	4.9	5.6
Separative work units net of liability	12.4	7.8
Uranium inventory net of liability	47.5	51.1
Inventories, net	$ 59.9	$ 58.9

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://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section 45
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=118951113&loc=d3e6676-107765

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 330
-SubTopic 10
-Section 35
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=116846819&loc=d3e3927-108312

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-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

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