Debt (Details) (USD $)	3 Months Ended
	Mar. 31, 2015	Dec. 31, 2014
Lines of Credit [Abstract]
Available and unused credit lines	$ 3,408,900,000	$ 3,437,800,000
Short-Term Borrowings [Abstract]
Short-term borrowings	9,600,000	7,200,000
Long-Term Notes Payable [Abstract]
Long-term notes payable, carrying amount	4,500,300,000	4,500,500,000
Unamortized premium (discount) on Senior Notes, net	10,900,000	11,100,000
Adjustment to carrying value for interest rate swaps	82,900,000	51,400,000
Long-term notes payable, total	4,594,100,000	4,563,000,000
Long-term notes payable, current portion	(300,000)	(400,000)
Long-Term Notes Payable	4,593,800,000	4,562,600,000
Interest rate swaps, fair value	76,000,000	42,700,000
Credit Agreement expiring July 31, 2019 [Member]
Lines of Credit [Abstract]
Credit Agreement, maximum borrowing capacity	2,500,000,000
Credit Agreement, expiration date	Jul. 31, 2019
Available and unused credit lines	2,500,000,000	2,500,000,000
Credit Agreement, covenant terms	The Credit Agreement contains financial covenants that require us to maintain a Leverage Ratio of consolidated indebtedness to consolidated EBITDA of no more than 3 times for the most recently ended 12-month period (under the Credit Agreement, EBITDA is defined as earnings before interest, taxes, depreciation and amortization) and an Interest Coverage Ratio of consolidated EBITDA to interest expense of at least 5 times for the most recently ended 12-month period.
Credit Agreement, covenant compliance	At March 31, 2015, we were in compliance with these covenants, as our Leverage Ratio was 2.0 times and our Interest Coverage Ratio was 12.9 times.
Credit Agreement expiring July 31, 2019 [Member] | Commercial Paper [Member]
Lines of Credit [Abstract]
Credit Agreement, maximum borrowing capacity	2,000,000,000
Uncommitted lines of credit [Member]
Lines of Credit [Abstract]
Available and unused credit lines	908,900,000	937,800,000
5.9% Senior Notes due 2016
Long-Term Notes Payable [Abstract]
Long-term notes payable, carrying amount	1,000,000,000	1,000,000,000
Interest rate	5.90%
Maturity date	Apr. 15, 2016
6.25% Senior Notes due 2019
Long-Term Notes Payable [Abstract]
Long-term notes payable, carrying amount	500,000,000	500,000,000
Interest rate	6.25%
Maturity date	Jul. 15, 2019
4.45% Senior Notes due 2020
Long-Term Notes Payable [Abstract]
Long-term notes payable, carrying amount	1,000,000,000	1,000,000,000
Interest rate	4.45%
Maturity date	Aug. 15, 2020
3.625% Senior Notes due 2022
Long-Term Notes Payable [Abstract]
Long-term notes payable, carrying amount	1,250,000,000	1,250,000,000
Interest rate	3.625%
Maturity date	May 01, 2022
3.65% Senior Notes due 2024
Long-Term Notes Payable [Abstract]
Long-term notes payable, carrying amount	750,000,000	750,000,000
Interest rate	3.65%
Maturity date	Nov. 01, 2024
Other notes and loans
Long-Term Notes Payable [Abstract]
Long-term notes payable, carrying amount	300,000	500,000
Interest Rate Swaps on 2022 Notes [Member]
Long-Term Notes Payable [Abstract]
Interest rate swaps, hedged amount	1,250,000,000
Interest Rate Swaps on 2020 Notes [Member]
Long-Term Notes Payable [Abstract]
Interest rate swaps, hedged amount	$ 1,000,000,000
LIBOR [Member] | Interest Rate Swaps on 2022 Notes [Member]
Long-Term Notes Payable [Abstract]
Interest rate swaps, spread	1.05%
LIBOR [Member] | Interest Rate Swaps on 2020 Notes [Member]
Long-Term Notes Payable [Abstract]
Interest rate swaps, spread	2.16%