Derivative Financial Instruments and Related Hedging Programs, Offsetting of Derivative Instruments by Counterparty (Details) (USD $) In Millions, unless otherwise specified	Jun. 30, 2013		Dec. 31, 2012
Derivative Assets and Collateral Held by Counterparty
Gross Amounts of Recognized Assets	$ 53.8		$ 58.5
Gross Amounts Offset in the Consolidated Balance Sheets	0		0
Net Amounts of Assets Presented in the Consolidated Balance Sheets	53.8		58.5
Gross Amounts Not Offset in the Consolidated Balance Sheets
Financial Instruments	1.4		1.2
Cash Collateral Received	0		0
Net Amount	52.4		57.3
Derivative Liabilities and Collateral Held by Counterparty
Gross Amounts of Recognized Liabilities	(67.3)		(66.7)
Gross Amounts Offset in the Consolidated Balance Sheets	0		0
Net Amounts of Liabilities Presented in the Consolidated Balance Sheets	67.3		66.7
Gross Amounts Not Offset in the Consolidated Balance Sheets
Financial Instruments	(1.4)		(1.2)
Cash Collateral Pledged	0		0
Net Amount	(65.9)		(65.5)
Counterparty (with Netting Agreements)
Derivative Assets and Collateral Held by Counterparty
Gross Amounts of Recognized Assets	1.0		2.3
Gross Amounts Offset in the Consolidated Balance Sheets	0		0
Net Amounts of Assets Presented in the Consolidated Balance Sheets	1.0		2.3
Gross Amounts Not Offset in the Consolidated Balance Sheets
Financial Instruments	1.0		1.0
Cash Collateral Received	0		0
Net Amount	0		1.3
Derivative Liabilities and Collateral Held by Counterparty
Gross Amounts of Recognized Liabilities	(4.1)		(1.7)
Gross Amounts Offset in the Consolidated Balance Sheets	0		0
Net Amounts of Liabilities Presented in the Consolidated Balance Sheets	4.1		1.7
Gross Amounts Not Offset in the Consolidated Balance Sheets
Financial Instruments	(1.0)		(1.0)
Cash Collateral Pledged	0		0
Net Amount	(3.1)		(0.7)
Counterparty (without Netting Agreements)
Derivative Assets and Collateral Held by Counterparty
Gross Amounts of Recognized Assets	52.2	[1]	55.9	[2]
Gross Amounts Offset in the Consolidated Balance Sheets	0	[1]	0	[2]
Net Amounts of Assets Presented in the Consolidated Balance Sheets	52.2	[1]	55.9	[2]
Gross Amounts Not Offset in the Consolidated Balance Sheets
Financial Instruments	0	[1]	0	[2]
Cash Collateral Received	0	[1]	0	[2]
Net Amount	52.2	[1]	55.9	[2]
Derivative Liabilities and Collateral Held by Counterparty
Gross Amounts of Recognized Liabilities	(60.9)	[1]	(63.8)	[2]
Gross Amounts Offset in the Consolidated Balance Sheets	0	[1]	0	[2]
Net Amounts of Liabilities Presented in the Consolidated Balance Sheets	60.9	[1]	63.8	[2]
Gross Amounts Not Offset in the Consolidated Balance Sheets
Financial Instruments	0	[1]	0	[2]
Cash Collateral Pledged	0	[1]	0	[2]
Net Amount	(60.9)	[1]	(63.8)	[2]
Counterparty (with partial Netting Agreements)
Derivative Assets and Collateral Held by Counterparty
Gross Amounts of Recognized Assets	0.6		0.3
Gross Amounts Offset in the Consolidated Balance Sheets	0		0
Net Amounts of Assets Presented in the Consolidated Balance Sheets	0.6		0.3
Gross Amounts Not Offset in the Consolidated Balance Sheets
Financial Instruments	0.4		0.2
Cash Collateral Received	0		0
Net Amount	0.2		0.1
Derivative Liabilities and Collateral Held by Counterparty
Gross Amounts of Recognized Liabilities	(2.3)		(1.2)
Gross Amounts Offset in the Consolidated Balance Sheets	0		0
Net Amounts of Liabilities Presented in the Consolidated Balance Sheets	2.3		1.2
Gross Amounts Not Offset in the Consolidated Balance Sheets
Financial Instruments	(0.4)		(0.2)
Cash Collateral Pledged	0		0
Net Amount	$ (1.9)		$ (1.0)

[1] Such amounts include the fair value of the Company’s Call Options and Bifurcated Conversion Feature at June 30, 2013 (see Note 10).

[2] Such amounts include the fair value of the Company’s Call Options and Bifurcated Conversion Feature at December 31, 2012 (see Note 10).