Long-Term Debt (Details) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Debt Instrument Table [Line Items]
Total Long-Term Debt	$ 6,290,000,000	$ 5,040,000,000
Current Portion of Long-Term Debt	406,579,000	0
Unamortized Debt Discount	40,787,000	30,834,000
Total Long-Term Debt, Net	5,905,602,000	5,009,166,000
Long-Term Debt by Maturity [Abstract]
Aggregate annual maturity of long-term debt in 2013	400,000,000
Aggregate annual maturity of long-term debt in 2014	500,000,000
Aggregate annual maturity of long-term debt in 2015	500,000,000
Aggregate annual maturity of long-term debt in 2016	400,000,000
Aggregate annual maturity of long-term debt in 2017	600,000,000
Line of Credit Facility [Line Items]
Base rate at period end (in hundredths)	3.25%
Capital Lease [Abstract]
Capital Lease Term (in years)	10
Capital Lease Optional Additional Term (in years)	5
Capital Lease Obligations	62,968,000	0
Capital Lease Obligations, Noncurrent	56,000,000
Capital Lease Obligations, Current	7,000,000
Capital Leases, Future Minimum Payments Due	72,000,000
Uncommitted Credit Facility [Member]
Line of Credit Facility [Line Items]
Average Borrowings Outstanding	41,000
Weighted average interest rate (in hundredths)	0.70%
Commercial Paper [Member]
Line of Credit Facility [Line Items]
Average Borrowings Outstanding	236,000,000
Weighted average interest rate (in hundredths)	0.45%
Revolving Credit Agreement 2011 [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Expiration Date	Oct. 11, 2016
Maximum borrowing capacity	2,000,000,000
Eurodollar rate at period end (in hundredths)	1.08%
Maximum total debt-to-total capitalization ratio allowed under financial covenant (in hundredths)	65.00%
Advances up to an aggregate principal amount	2,000,000,000
Increases in the aggregate commitments to an amount not to exceed	3,000,000,000
Senior Notes Due 2013 [Member]
Debt Instrument Table [Line Items]
Total Long-Term Debt	400,000,000	400,000,000
Floating Rate Senior Notes Due 2014 [Member]
Debt Instrument Table [Line Items]
Total Long-Term Debt	350,000,000	350,000,000
Senior Notes Due 2015 [Member]
Debt Instrument Table [Line Items]
Total Long-Term Debt	500,000,000	500,000,000
Senior Notes Due 2016 [Member]
Debt Instrument Table [Line Items]
Total Long-Term Debt	400,000,000	400,000,000
Senior Notes Due 2017 [Member]
Debt Instrument Table [Line Items]
Total Long-Term Debt	600,000,000	600,000,000
Senior Notes Due 2018 [Member]
Debt Instrument Table [Line Items]
Total Long-Term Debt	350,000,000	350,000,000
Senior Notes Due 2019 [Member]
Debt Instrument Table [Line Items]
Total Long-Term Debt	900,000,000	900,000,000
Senior Notes Due 2020 [Member]
Debt Instrument Table [Line Items]
Total Long-Term Debt	500,000,000	500,000,000
Senior Notes Due 2021 [Member]
Debt Instrument Table [Line Items]
Total Long-Term Debt	750,000,000	750,000,000
Senior Notes Due 2023 [Member]
Debt Instrument Table [Line Items]
Total Long-Term Debt	1,250,000,000	0
Debt Instrument Issuance [Abstract]
Debt Instrument Offering Date	Sep. 10, 2012
Debt Instrument Issuance Face Amount	1,250,000,000
Debt Instrument Issuance Interest Rate	2.625%
Debt Instrument Frequency of Periodic Payment	semi-annually
Proceeds From Issuance of Senior Long-Term Debt	1,234,000,000
Effective Interest Rate (in hundredths)	2.784%
Senior Notes Due 2028 [Member]
Debt Instrument Table [Line Items]
Total Long-Term Debt	140,000,000	140,000,000
Subsidiary Debt Due 2014 [Member]
Debt Instrument Table [Line Items]
Total Long-Term Debt	150,000,000	150,000,000
Subsidiary Debt Due 2014 (Canadian)	201,300,000
Interest Rate - Canadian Subsidiary Note	5.275%
Debt Instrument Issuance [Abstract]
Debt Instrument, Maturity Date	Mar. 15, 2014
Debt Instrument Issuance Face Amount	$ 150,000,000
Debt Instrument Issuance Interest Rate	4.75%