Borrowings and Capital Leases (Senior Notes Issued by SAIIDAC) (Details) - USD ($)	Dec. 31, 2017	Sep. 23, 2016
Debt Instrument [Line Items]
Carrying amount	$ 19,635,400,000
SAIIDAC notes | Senior Notes
Debt Instrument [Line Items]
Aggregate amount	12,100,000,000
Carrying amount	12,050,200,000
SAIIDAC notes | Senior Notes | Fixed-rate notes due 2019
Debt Instrument [Line Items]
Aggregate amount	$ 3,300,000,000
Coupon rate	1.90%	1.90%
Effective Interest Rate	2.05%
Carrying amount	$ 3,291,900,000
SAIIDAC notes | Senior Notes | Fixed-rate notes due 2021
Debt Instrument [Line Items]
Aggregate amount	$ 3,300,000,000
Coupon rate	2.40%	2.40%
Effective Interest Rate	2.53%
Carrying amount	$ 3,286,400,000
SAIIDAC notes | Senior Notes | Fixed-rate notes due 2023
Debt Instrument [Line Items]
Aggregate amount	$ 2,500,000,000
Coupon rate	2.875%	2.875%
Effective Interest Rate	2.97%
Carrying amount	$ 2,489,500,000
SAIIDAC notes | Senior Notes | Fixed-rate notes due 2026
Debt Instrument [Line Items]
Aggregate amount	$ 3,000,000,000
Coupon rate	3.20%	3.20%
Effective Interest Rate	3.30%
Carrying amount	$ 2,982,400,000