Equity - Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning Balance	$ 34,414	$ 34,876
Other comprehensive income (loss) before reclassifications	(271)	171
Amounts reclassified from accumulated other comprehensive income (loss)	11	1
Deferred taxes	(4)	0
Other comprehensive income (loss)	(264)	172
Less: Other comprehensive income (loss) attributable to noncontrolling interests	0	0
Ending Balance	17,985	34,966
Investment Securities, Parent
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning Balance	2	0
Ending Balance	0	2
Investment Securities
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Other comprehensive income (loss) before reclassifications	(2)	2
Amounts reclassified from accumulated other comprehensive income (loss)	0	0
Deferred taxes	0	0
Other comprehensive income (loss)	(2)	2
Investment Securities, Noncontrolling Interest
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Less: Other comprehensive income (loss) attributable to noncontrolling interests	0	0
Foreign Currency Translation Adjustment, Parent
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning Balance	(2,274)	(2,326)
Ending Balance	(2,551)	(2,160)
Foreign Currency Translation Adjustments
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Other comprehensive income (loss) before reclassifications	(277)	166
Amounts reclassified from accumulated other comprehensive income (loss)	0	0
Deferred taxes		0
Other comprehensive income (loss)	(277)	166
Foreign Currency Translation Adjustments, Noncontrolling Interest
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Less: Other comprehensive income (loss) attributable to noncontrolling interests	0	0
Cash Flow Hedges, Parent
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning Balance	10	(3)
Ending Balance	2
Cash Flow Hedges
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Other comprehensive income (loss) before reclassifications	(9)	5
Amounts reclassified from accumulated other comprehensive income (loss)	0	0
Deferred taxes	1	(1)
Other comprehensive income (loss)	(8)	4
Ending Balance		1
Cash Flow Hedges, Noncontrolling Interest
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Less: Other comprehensive income (loss) attributable to noncontrolling interests	0	0
Benefit Plans, Parent
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning Balance	(327)	(133)
Ending Balance	(304)	(133)
Benefit Plans
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Other comprehensive income (loss) before reclassifications	17	(2)
Amounts reclassified from accumulated other comprehensive income (loss)	11	1
Deferred taxes	(5)	1
Other comprehensive income (loss)	23	0
Benefit Plans, Noncontrolling Interest
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Less: Other comprehensive income (loss) attributable to noncontrolling interests	0	0
Accumulated Other Comprehensive Loss
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning Balance	(2,589)	(2,462)
Other comprehensive income (loss)	(264)	172
Ending Balance	$ (2,853)	$ (2,290)