Borrowings (Schedule of Senior Unsecured Notes) (Details) - Senior Unsecured Notes [Member] - USD ($)	6 Months Ended
	Jun. 30, 2017	Apr. 04, 2017
Debt Instrument [Line Items]
Par Value	$ 4,531,000,000
Weighted Average Rate (%)	4.90%
February 2019 - 5.500% [Member]
Debt Instrument [Line Items]
Rate (%)	5.50%	5.50%
Date of Issuance	Feb. 01, 2012
Par Value	$ 781,000,000
February 2019 - 3.875% [Member]
Debt Instrument [Line Items]
Rate (%)	3.875%
Date of Issuance	Feb. 01, 2014
Par Value	$ 1,000,000,000
May 2020 - 5.375% [Member]
Debt Instrument [Line Items]
Rate (%)	5.375%	5.375%
Date of Issuance	May 01, 2012
Par Value	$ 750,000,000
August 2022 - 5.000% [Member]
Debt Instrument [Line Items]
Rate (%)	5.00%	5.00%
Date of Issuance	Aug. 01, 2012
Par Value	$ 1,250,000,000
August 2023 - 5.000% [Member]
Debt Instrument [Line Items]
Rate (%)	5.00%
Date of Issuance	Aug. 01, 2013
Par Value	$ 750,000,000