Fair Value Disclosures (Fair Value Of Certain Short And Long-term Debt, Based On Market Prices) (Details) (USD $) In Millions	6 Months Ended	12 Months Ended
Jun. 30, 2011	Dec. 31, 2010
Fair Value Disclosures
Medium-term notes at Fair Value	$ 1,673.4	$ 1,650.7
Medium-term notes at Book Value	1,622.2	1,623.0
Preferred securities underlying the junior convertible subordinated debentures at Fair Value	396.0	353.8
Preferred securities underlying the junior convertible subordinated debentures at Book Value	$ 421.2	$ 421.2

Including the current and noncurrent portions, carrying value at the balance sheet date of a financial instrument used to receive debt funding on a regular basis with original maturities ranging from 5-10 years.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 03
-Paragraph 16
-Article 9

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 02
-Paragraph 20, 22
-Article 5

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Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant