Long-term Debt (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended			9 Months Ended
	Sep. 30, 2014		Sep. 30, 2013	Sep. 30, 2014		Sep. 30, 2013	Dec. 31, 2013
Debt Instrument [Line Items]
(Gain) loss related to early extinguishment of debt	$ 0		$ (45.2)	$ (10.4)		$ (45.2)
Discount				350.1		601.2
Long-term Debt	1,629.0			1,629.0			1,483.4
Less: current portion	2.2	[1]		2.2	[1]		353.6	[1]
Long-term Debt, Excluding Current Maturities	1,626.8			1,626.8			1,129.8
Proceeds from Issuance of Long-term Debt				499.1		0
6.25% Notes
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Effective Percentage	6.29%			6.29%
Debt Instrument, Interest Rate, Stated Percentage	6.25%			6.25%
Early Repayment of Senior Debt				371.2
(Gain) loss related to early extinguishment of debt				(10.4)
Interest Paid, Net				10.3
Debt Instrument, Face Amount	350.0			350.0
Debt Instrument, Maturity Date				Nov. 15, 2014
Debt Instrument, Unamortized Discount	0			0
Long-term Debt, Gross	0			0			351.3
Long-term Debt, Fair Value	0	[2]		0	[2]		365.6	[2]
2.25% Notes
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Effective Percentage	2.30%			2.30%
Debt Instrument, Interest Rate, Stated Percentage	2.25%			2.25%
Debt Instrument, Maturity Date				Nov. 15, 2017
Debt Instrument, Unamortized Discount	0.5			0.5
Long-term Debt, Gross	299.5			299.5			299.4
Long-term Debt, Fair Value	300.8	[2]		300.8	[2]		293.0	[2]
4.00% Notes
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Effective Percentage	4.13%			4.13%
Debt Instrument, Interest Rate, Stated Percentage	4.00%			4.00%
Debt Instrument, Maturity Date				Mar. 15, 2022
Debt Instrument, Unamortized Discount	2.3			2.3
Long-term Debt, Gross	247.7			247.7			247.4
Long-term Debt, Fair Value	254.7	[2]		254.7	[2]		241.6	[2]
3.75% Notes
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Effective Percentage	4.32%			4.32%
Debt Instrument, Interest Rate, Stated Percentage	3.75%			3.75%
Debt Instrument, Maturity Date				Feb. 15, 2023
Debt Instrument, Unamortized Discount	1.3			1.3
Long-term Debt, Gross	498.7			498.7			498.6
Long-term Debt, Fair Value	496.2	[2]		496.2	[2]		467.3	[2]
4.20% Notes
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Effective Percentage	4.24%			4.24%
Debt Instrument, Interest Rate, Stated Percentage	4.20%			4.20%
Discount				0.9
Debt Instrument, Face Amount	500.0			500.0
Debt Instrument, Maturity Date				Apr. 15, 2024
Debt Instrument, Unamortized Discount	0.9			0.9
Fees and Commissions				4.4
Long-term Debt, Gross	499.1			499.1			0
Long-term Debt, Fair Value	506.7	[2]		506.7	[2]		0	[2]
Proceeds from Issuance of Long-term Debt				494.7
Debt Instrument, Frequency of Periodic Payment				semi-annually
Other notes payable and capitalized leases
Debt Instrument [Line Items]
Long-term Debt, Gross	84.0			84.0			86.7
Long-term Debt, Fair Value	$ 86.6	[2]		$ 86.6	[2]		$ 87.8	[2]

[1] We included our 6.25% Senior Unsecured Notes due 2014 (the "6.25% Notes") in the current portion of long-term debt on our December 31, 2013 Consolidated Balance Sheet because the 6.25% Notes were scheduled to mature on November 15, 2014. We redeemed the 6.25% Notes prior to their scheduled maturity during the second quarter of 2014.

[2] See Note 12 for information on the fair value measurement of our long-term debt.