Derivatives, Gross Fair Value of Derivative Assets and Liabilities (Details) - USD ($) $ in Millions	6 Months Ended	12 Months Ended
	Jun. 30, 2019	Dec. 31, 2018
Derivative Assets
Gross amounts recognized	$ 40,050	$ 34,560
Gross amounts offset in consolidated balance sheet	(26,888)	(23,790)
Net amounts in consolidated balance sheet, assets	13,162	10,770
Gross amounts not offset in consolidated balance sheet (Disclosure-only netting)	(357)	(875)
Net amounts	12,805	9,895
Derivative Liabilities
Gross amounts recognized	38,116	32,047
Gross amounts offset in consolidated balance sheet, liabilities	(29,717)	(23,548)
Net amounts in consolidated balance sheet, liabilities	8,399	8,499
Gross amounts not offset in consolidated balance sheet (Disclosure-only netting)	(1,262)	(875)
Net amounts	7,137	7,624
Derivatives (Textual) [Abstract]
Derivative assets subject to enforceable master netting arrangements	35,100	30,900
Derivative liabilities subject to enforceable master netting arrangements	34,900	28,400
Derivative assets not subject to enforceable master netting arrangements	5,000	3,700
Derivative liabilities not subject to enforceable master netting arrangements	3,200	3,600
Valuation adjustments for derivative assets	301	353
Valuation adjustments for derivative liabilities	92	152
Cash collateral netted against derivative assets	3,600	3,700
Cash collateral netted against derivative liabilities	6,600	3,600
Interest rate contract [Member]
Derivative Assets
Gross amounts recognized	25,553	18,435
Gross amounts offset in consolidated balance sheet	(16,558)	(12,029)
Net amounts in consolidated balance sheet, assets	8,995	6,406
Gross amounts not offset in consolidated balance sheet (Disclosure-only netting)	(313)	(80)
Net amounts	$ 8,682	$ 6,326
Percent exchanged in the over the counter market	95.00%	90.00%
Derivative Liabilities
Gross amounts recognized	$ 20,637	$ 16,308
Gross amounts offset in consolidated balance sheet, liabilities	(18,046)	(13,152)
Net amounts in consolidated balance sheet, liabilities	2,591	3,156
Gross amounts not offset in consolidated balance sheet (Disclosure-only netting)	(848)	(567)
Net amounts	$ 1,743	$ 2,589
Percent exchanged in over-the-counter market	95.00%	92.00%
Commodity contract [Member]
Derivative Assets
Gross amounts recognized	$ 1,424	$ 1,588
Gross amounts offset in consolidated balance sheet	(951)	(849)
Net amounts in consolidated balance sheet, assets	473	739
Gross amounts not offset in consolidated balance sheet (Disclosure-only netting)	(1)	(4)
Net amounts	$ 472	$ 735
Percent exchanged in the over the counter market	73.00%	57.00%
Derivative Liabilities
Gross amounts recognized	$ 1,936	$ 2,336
Gross amounts offset in consolidated balance sheet, liabilities	(738)	(727)
Net amounts in consolidated balance sheet, liabilities	1,198	1,609
Gross amounts not offset in consolidated balance sheet (Disclosure-only netting)	0	(8)
Net amounts	$ 1,198	$ 1,601
Percent exchanged in over-the-counter market	81.00%	85.00%
Equity contract [Member]
Derivative Assets
Gross amounts recognized	$ 7,377	$ 7,545
Gross amounts offset in consolidated balance sheet	(5,041)	(5,318)
Net amounts in consolidated balance sheet, assets	2,336	2,227
Gross amounts not offset in consolidated balance sheet (Disclosure-only netting)	(34)	(755)
Net amounts	$ 2,302	$ 1,472
Percent exchanged in the over the counter market	71.00%	78.00%
Derivative Liabilities
Gross amounts recognized	$ 9,178	$ 6,010
Gross amounts offset in consolidated balance sheet, liabilities	(5,934)	(3,877)
Net amounts in consolidated balance sheet, liabilities	3,244	2,133
Gross amounts not offset in consolidated balance sheet (Disclosure-only netting)	(214)	(110)
Net amounts	$ 3,030	$ 2,023
Percent exchanged in over-the-counter market	84.00%	75.00%
Foreign exchange contract [Member]
Derivative Assets
Gross amounts recognized	$ 5,555	$ 6,714
Gross amounts offset in consolidated balance sheet	(4,250)	(5,355)
Net amounts in consolidated balance sheet, assets	1,305	1,359
Gross amounts not offset in consolidated balance sheet (Disclosure-only netting)	(8)	(35)
Net amounts	$ 1,297	$ 1,324
Percent exchanged in the over the counter market	100.00%	100.00%
Derivative Liabilities
Gross amounts recognized	$ 6,268	$ 7,113
Gross amounts offset in consolidated balance sheet, liabilities	(4,918)	(5,522)
Net amounts in consolidated balance sheet, liabilities	1,350	1,591
Gross amounts not offset in consolidated balance sheet (Disclosure-only netting)	(197)	(188)
Net amounts	$ 1,153	$ 1,403
Percent exchanged in over-the-counter market	100.00%	100.00%
Credit Contracts Protection Sold [Member]
Derivative Assets
Gross amounts recognized	$ 15	$ 76
Gross amounts offset in consolidated balance sheet	(9)	(73)
Net amounts in consolidated balance sheet, assets	6	3
Gross amounts not offset in consolidated balance sheet (Disclosure-only netting)	0	0
Net amounts	$ 6	$ 3
Percent exchanged in the over the counter market	74.00%	12.00%
Derivative Liabilities
Gross amounts recognized	$ 80	$ 182
Gross amounts offset in consolidated balance sheet, liabilities	(75)	(180)
Net amounts in consolidated balance sheet, liabilities	5	2
Gross amounts not offset in consolidated balance sheet (Disclosure-only netting)	(3)	(2)
Net amounts	$ 2	$ 0
Percent exchanged in over-the-counter market	99.00%	67.00%
Credit Contracts Protection Purchased [Member]
Derivative Assets
Gross amounts recognized	$ 126	$ 202
Gross amounts offset in consolidated balance sheet	(79)	(166)
Net amounts in consolidated balance sheet, assets	47	36
Gross amounts not offset in consolidated balance sheet (Disclosure-only netting)	(1)	(1)
Net amounts	$ 46	$ 35
Percent exchanged in the over the counter market	99.00%	78.00%
Derivative Liabilities
Gross amounts recognized	$ 17	$ 98
Gross amounts offset in consolidated balance sheet, liabilities	(6)	(90)
Net amounts in consolidated balance sheet, liabilities	11	8
Gross amounts not offset in consolidated balance sheet (Disclosure-only netting)	0	0
Net amounts	$ 11	$ 8
Percent exchanged in over-the-counter market	98.00%	11.00%