Shareholders' Equity - Schedule of Accumulated Other Comprehensive (Loss) Income (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Equity [Abstract]
Net unrealized gains (losses) on cash flow hedges	$ (56)	$ 229	$ 293
Net unrealized gains (losses) on available-for-sale securities portfolio	148	(225)	9
Net unrealized gains (losses) related to reclassified available-for-sale securities	19	25	(28)
Net unrealized gains (losses) on available-for-sale securities	167	(200)	(19)
Net unrealized losses on available-for-sale securities designated in fair value hedges	(64)	(86)	(109)
Net unrealized gains (losses) on hedges of net investments in non-U.S. subsidiaries	(65)	95	(14)
Other-than-temporary impairment on held-to-maturity securities related to factors other than credit	(6)	(9)	(16)
Net unrealized losses on retirement plans	(170)	(194)	(183)
Foreign currency translation	(815)	(1,875)	(1,394)
Total	$ (1,009)	$ (2,040)	$ (1,442)