Shareholders' Equity - Schedule of Accumulated Other Comprehensive (Loss) Income (Details) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Equity [Abstract]
Net unrealized (losses) on cash flow hedges	$ (83)	$ (56)
Net unrealized (losses) gains on available-for-sale securities portfolio	(330)	148
Net unrealized gains related to reclassified available-for-sale securities	22	19
Net unrealized (losses) gains on available-for-sale securities	(308)	167
Net unrealized (losses) on available-for-sale securities designated in fair value hedges	(35)	(64)
Net unrealized (losses) on hedges of net investments in non-U.S. subsidiaries	(11)	(65)
Other-than-temporary impairment on held-to-maturity securities related to factors other than credit	(5)	(6)
Net unrealized (losses) on retirement plans	(156)	(170)
Foreign currency translation	(1,113)	(815)
Total	$ (1,711)	$ (1,009)