Long-Term Debt (Details) - Notes Payable [Member]	1 Months Ended
	Feb. 28, 2017 USD ($)
Floating Rate Notes due 2019 [Member]
Debt Instrument [Line Items]
Debt instrument, face amount	$ 450,000,000
1.686% Notes due 2019 [Member]
Debt Instrument [Line Items]
Debt instrument, face amount	$ 550,000,000
Debt instrument, interest rate, stated percentage	1.686%
Floating Rate Notes due 2020 [Member]
Debt Instrument [Line Items]
Debt instrument, face amount	$ 400,000,000
1.991% Notes due 2020 [Member]
Debt Instrument [Line Items]
Debt instrument, face amount	$ 600,000,000
Debt instrument, interest rate, stated percentage	1.991%
Floating Rate Notes due 2022 [Member]
Debt Instrument [Line Items]
Debt instrument, face amount	$ 300,000,000
2.498% Notes due 2022 [Member]
Debt Instrument [Line Items]
Debt instrument, face amount	$ 700,000,000
Debt instrument, interest rate, stated percentage	2.498%
2.895% Notes due 2024 [Member]
Debt Instrument [Line Items]
Debt instrument, face amount	$ 1,000,000,000
Debt instrument, interest rate, stated percentage	2.895%
0.889% Notes due 2016 [Member]
Debt Instrument [Line Items]
Extinguishment of debt, amount	$ 900,000,000