Long-Term Debt (Debt Borrowings)(Details) - Senior Notes [Member] - USD ($) $ in Millions	Aug. 31, 2017	Jun. 30, 2017	Mar. 31, 2017	Jan. 31, 2017
Senior 3.15% Notes Due 2028 [Member]
Debt Instrument [Line Items]
Debt face amount	$ 1,650
Interest rate	3.15%
Senior 4.00% Notes Due 2047 [Member]
Debt Instrument [Line Items]
Debt face amount	$ 850
Interest rate	4.00%
Floating Rate Notes Due 2021 [Member]
Debt Instrument [Line Items]
Debt face amount		$ 1,500
Senior 4.45% Notes Due 2047 [Member]
Debt Instrument [Line Items]
Debt face amount			$ 1,005
Interest rate			4.45%
Senior 3.0% Notes Due 2024 [Member]
Debt Instrument [Line Items]
Debt face amount				$ 1,250
Interest rate				3.00%
Senior 3.3% Notes Due 2027 [Member]
Debt Instrument [Line Items]
Debt face amount				$ 1,250
Interest rate				3.30%