Subsequent Event (Narrative) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
Mar. 31, 2013
Subsequent Events
Preliminary purchase price for NAC	$ 42.4
Contract gross price for NAC	45.0
Working capital adjustment for NAC	2.6
Preliminary cash proceeds for sale of NAC	39.9
Estimated gain on sale of NAC, minimum	30.0
Estimated gain on sale of NAC, maximum	$ 40.0

This item represents the amount of net sales proceeds received on disposal of an equity method investment.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 323

-SubTopic 10

-Section 35

-Paragraph 35

-URI http://asc.fasb.org/extlink&oid=7658923&loc=d3e32847-111569

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration