Long-Term Debt (Narrative) (Details) - USD ($) $ in Millions | Sep. 06, 2016 | Mar. 01, 2016 | Feb. 12, 2016 | Sep. 15, 2015 | May 28, 2015 | Oct. 30, 2016 | Jan. 31, 2016 |
Debt Instrument [Line Items] | | | | | | | |
Debt Instrument, Redemption Price | | | | | | 100.00% | |
Debt Instrument, Change of Control, Redemption Price, Percent | | | | | | 101.00% | |
2.125% Senior Notes Due September 15, 2026 [Member] | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Debt Instrument, Face Amount | $ 1,000 | | | | | | |
Debt Instrument, Interest Rate, Stated Percentage | 2.125% | | | | | | |
Debt Instrument, Maturity Date | Sep. 15, 2026 | | | | | | |
Debt Discount | $ 11 | | | | | | |
Debt Instrument, Frequency of Periodic Payment | semi-annually on March 15 and September 15 | | | | | | |
3.50% Senior Notes Due September 15, 2056 [Member] | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Debt Instrument, Face Amount | $ 1,000 | | | | | | |
Debt Instrument, Interest Rate, Stated Percentage | 3.50% | | | | | | |
Debt Instrument, Maturity Date | Sep. 15, 2056 | | | | | | |
Debt Discount | $ 19 | | | | | | |
Debt Instrument, Frequency of Periodic Payment | semi-annually on March 15 and September 15 | | | | | | |
September 2016 Issuance [Member] | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Debt Discount | $ 30 | | | | | | |
Debt Issuance Costs, Gross | $ 16 | | | | | | |
2.00% Senior Notes Due April 1, 2021 [Member] | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Debt Instrument, Face Amount | | | $ 1,350 | | | | |
Debt Instrument, Interest Rate, Stated Percentage | | | 2.00% | | | | |
Debt Instrument, Maturity Date | | | Apr. 1, 2021 | | | | |
Debt Discount | | | $ 5 | | | | |
Debt Instrument, Frequency of Periodic Payment | | | semi-annually on April 1 and October 1 | | | | |
3.00% Senior Notes Due April 1, 2026 [Member] | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Debt Instrument, Face Amount | | | $ 1,300 | | | | |
Debt Instrument, Interest Rate, Stated Percentage | | | 3.00% | | | | |
Debt Instrument, Maturity Date | | | Apr. 1, 2026 | | | | |
Debt Discount | | | $ 8 | | | | |
Debt Instrument, Frequency of Periodic Payment | | | semi-annually on April 1 and October 1 | | | | |
February 2016 Issuance [Member] | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Debt Discount | | | $ 13 | | | | |
Debt Issuance Costs, Gross | | | 17 | | | | |
February 2016 Issuance [Member] | Interest Rate Swap [Member] | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Derivative, Notional Amount | | | | | | | $ 1,000 |
Loss on forward starting interest rate swaps | | | 89 | | | | |
Additional 4.25% Senior Notes Due April 1, 2046 [Member] | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Debt Instrument, Face Amount | | | $ 350 | | | | |
Debt Instrument, Interest Rate, Stated Percentage | | | 4.25% | | | | |
Debt Instrument, Maturity Date | | | Apr. 1, 2046 | | | | |
Debt Premium | | | $ 2 | | | | |
Debt Instrument, Frequency of Periodic Payment | | | semi-annually on April 1 and October 1 | | | | |
4.25% Senior Notes Due April 1, 2046 [Member] | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Debt Instrument, Face Amount | | | $ 1,600 | | $ 1,250 | | |
Debt Instrument, Interest Rate, Stated Percentage | | | | | 4.25% | | |
Debt Instrument, Maturity Date | | | Apr. 1, 2046 | | Apr. 1, 2046 | | |
5.40% Senior Notes Due March 1, 2016 [Member] | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Debt Instrument, Interest Rate, Stated Percentage | | 5.40% | | | | | |
Debt Instrument, Maturity Date | | Mar. 1, 2016 | | | | | |
Floating Rate Senior Notes Due September 15, 2017 [Member] | | | | | | | |
Debt Instrument [Line Items] | | | | | | | |
Debt Instrument, Face Amount | | | | $ 500 | | | |
Debt Instrument, Maturity Date | | | | Sep. 15, 2017 | | | |