Debt Obligations, Debt Maturities (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Scheduled Maturities of Debt [Abstract]
2013	$ 650.0
2014	1,150.0
2015	1,300.0
2016	750.0
2017	800.0
After 2017	12,882.7
Total	17,532.7	16,179.3
Senior Notes [Member]
Scheduled Maturities of Debt [Abstract]
2013	650.0
2014	1,150.0
2015	1,300.0
2016	750.0
2017	800.0
After 2017	11,350.0
Total	16,000.0
Junior Subordinated Notes [Member]
Scheduled Maturities of Debt [Abstract]
2013	0
2014	0
2015	0
2016	0
2017	0
After 2017	1,532.7
Total	$ 1,532.7

Including current and noncurrent portions, aggregate carrying amount of long-term borrowings as of the balance sheet date before deducting unamortized discount or premiums (if any). May include notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt, which had initial maturities beyond one year or beyond the normal operating cycle, if longer.

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

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Reference 2: http://www.xbrl.org/2003/role/presentationRef

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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 3: http://www.xbrl.org/2003/role/presentationRef

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Reference 4: http://www.xbrl.org/2003/role/presentationRef

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Reference 5: http://www.xbrl.org/2003/role/presentationRef

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

-Publisher FASB

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