Derivative Instruments and Hedging Activities (Notional and Fair Value of Protection Sold and Purchased through Credit Default Swaps) (Details) - USD ($) $ in Millions	Sep. 30, 2015	Dec. 31, 2014
Protection Sold
Credit Derivatives
Derivative notional amount	$ 798,733	$ 909,273
Credit risk derivative (assets) / liability, fair value	(1,343)	(7,111)
Protection Sold | Less than 1 Year
Credit Derivatives
Derivative notional amount	164,282	188,408
Protection Sold | 1 - 3 Years
Credit Derivatives
Derivative notional amount	384,515	439,538
Protection Sold | 3 - 5 Years
Credit Derivatives
Derivative notional amount	171,998	233,887
Protection Sold | Over 5 Years
Credit Derivatives
Derivative notional amount	77,938	47,440
Protection Sold | Credit Default Swaps
Credit Derivatives
Derivative notional amount	797,537	908,062
Credit risk derivative (assets) / liability, fair value	(301)	(6,611)
Protection Sold | Credit Default Swaps | Less than 1 Year
Credit Derivatives
Derivative notional amount	164,281	188,357
Protection Sold | Credit Default Swaps | 1 - 3 Years
Credit Derivatives
Derivative notional amount	383,709	438,999
Protection Sold | Credit Default Swaps | 3 - 5 Years
Credit Derivatives
Derivative notional amount	171,658	233,886
Protection Sold | Credit Default Swaps | Over 5 Years
Credit Derivatives
Derivative notional amount	77,889	46,820
Protection Sold | Single Name Credit Default Swaps
Credit Derivatives
Derivative notional amount	458,768	535,415
Credit risk derivative (assets) / liability, fair value	1,241	(2,479)
Protection Sold | Single Name Credit Default Swaps | AAA
Credit Derivatives
Derivative notional amount	24,561	18,624
Credit risk derivative (assets) / liability, fair value	(253)	(113)
Protection Sold | Single Name Credit Default Swaps | AA
Credit Derivatives
Derivative notional amount	40,991	50,868
Credit risk derivative (assets) / liability, fair value	(433)	(688)
Protection Sold | Single Name Credit Default Swaps | A
Credit Derivatives
Derivative notional amount	68,706	100,179
Credit risk derivative (assets) / liability, fair value	(803)	(1,962)
Protection Sold | Single Name Credit Default Swaps | BBB
Credit Derivatives
Derivative notional amount	189,626	237,096
Credit risk derivative (assets) / liability, fair value	(325)	(1,489)
Protection Sold | Single Name Credit Default Swaps | Non-investment Grade
Credit Derivatives
Derivative notional amount	134,884	128,648
Credit risk derivative (assets) / liability, fair value	3,055	1,773
Protection Sold | Single Name Credit Default Swaps | Less than 1 Year
Credit Derivatives
Derivative notional amount	110,456	112,730
Protection Sold | Single Name Credit Default Swaps | Less than 1 Year | AAA
Credit Derivatives
Derivative notional amount	4,247	2,385
Protection Sold | Single Name Credit Default Swaps | Less than 1 Year | AA
Credit Derivatives
Derivative notional amount	9,247	9,080
Protection Sold | Single Name Credit Default Swaps | Less than 1 Year | A
Credit Derivatives
Derivative notional amount	18,861	22,861
Protection Sold | Single Name Credit Default Swaps | Less than 1 Year | BBB
Credit Derivatives
Derivative notional amount	43,071	48,547
Protection Sold | Single Name Credit Default Swaps | Less than 1 Year | Non-investment Grade
Credit Derivatives
Derivative notional amount	35,030	29,857
Protection Sold | Single Name Credit Default Swaps | 1 - 3 Years
Credit Derivatives
Derivative notional amount	227,722	265,842
Protection Sold | Single Name Credit Default Swaps | 1 - 3 Years | AAA
Credit Derivatives
Derivative notional amount	13,475	9,400
Protection Sold | Single Name Credit Default Swaps | 1 - 3 Years | AA
Credit Derivatives
Derivative notional amount	18,450	23,701
Protection Sold | Single Name Credit Default Swaps | 1 - 3 Years | A
Credit Derivatives
Derivative notional amount	36,875	52,291
Protection Sold | Single Name Credit Default Swaps | 1 - 3 Years | BBB
Credit Derivatives
Derivative notional amount	92,864	114,384
Protection Sold | Single Name Credit Default Swaps | 1 - 3 Years | Non-investment Grade
Credit Derivatives
Derivative notional amount	66,058	66,066
Protection Sold | Single Name Credit Default Swaps | 3 - 5 Years
Credit Derivatives
Derivative notional amount	97,724	132,639
Protection Sold | Single Name Credit Default Swaps | 3 - 5 Years | AAA
Credit Derivatives
Derivative notional amount	5,252	6,147
Protection Sold | Single Name Credit Default Swaps | 3 - 5 Years | AA
Credit Derivatives
Derivative notional amount	10,605	14,769
Protection Sold | Single Name Credit Default Swaps | 3 - 5 Years | A
Credit Derivatives
Derivative notional amount	11,145	22,083
Protection Sold | Single Name Credit Default Swaps | 3 - 5 Years | BBB
Credit Derivatives
Derivative notional amount	41,808	60,629
Protection Sold | Single Name Credit Default Swaps | 3 - 5 Years | Non-investment Grade
Credit Derivatives
Derivative notional amount	28,914	29,011
Protection Sold | Single Name Credit Default Swaps | Over 5 Years
Credit Derivatives
Derivative notional amount	22,866	24,204
Protection Sold | Single Name Credit Default Swaps | Over 5 Years | AAA
Credit Derivatives
Derivative notional amount	1,587	692
Protection Sold | Single Name Credit Default Swaps | Over 5 Years | AA
Credit Derivatives
Derivative notional amount	2,689	3,318
Protection Sold | Single Name Credit Default Swaps | Over 5 Years | A
Credit Derivatives
Derivative notional amount	1,825	2,944
Protection Sold | Single Name Credit Default Swaps | Over 5 Years | BBB
Credit Derivatives
Derivative notional amount	11,883	13,536
Protection Sold | Single Name Credit Default Swaps | Over 5 Years | Non-investment Grade
Credit Derivatives
Derivative notional amount	4,882	3,714
Protection Sold | Total Index and Basket Credit Default Swaps
Credit Derivatives
Derivative notional amount	338,769	372,647
Credit risk derivative (assets) / liability, fair value	(1,542)	(4,132)
Protection Sold | Total Index and Basket Credit Default Swaps | AAA
Credit Derivatives
Derivative notional amount	57,849	57,897
Credit risk derivative (assets) / liability, fair value	(1,006)	(985)
Protection Sold | Total Index and Basket Credit Default Swaps | AA
Credit Derivatives
Derivative notional amount		10,796
Credit risk derivative (assets) / liability, fair value		(270)
Protection Sold | Total Index and Basket Credit Default Swaps | A
Credit Derivatives
Derivative notional amount	15,651	18,308
Credit risk derivative (assets) / liability, fair value	(197)	(465)
Protection Sold | Total Index and Basket Credit Default Swaps | BBB
Credit Derivatives
Derivative notional amount	121,794	138,711
Credit risk derivative (assets) / liability, fair value	(818)	(2,904)
Protection Sold | Total Index and Basket Credit Default Swaps | Non-investment Grade
Credit Derivatives
Derivative notional amount	143,475	146,935
Credit risk derivative (assets) / liability, fair value	479	492
Protection Sold | Total Index and Basket Credit Default Swaps | Less than 1 Year
Credit Derivatives
Derivative notional amount	53,825	75,627
Protection Sold | Total Index and Basket Credit Default Swaps | Less than 1 Year | AAA
Credit Derivatives
Derivative notional amount	14,890	17,625
Protection Sold | Total Index and Basket Credit Default Swaps | Less than 1 Year | AA
Credit Derivatives
Derivative notional amount		704
Protection Sold | Total Index and Basket Credit Default Swaps | Less than 1 Year | A
Credit Derivatives
Derivative notional amount	4,700	1,283
Protection Sold | Total Index and Basket Credit Default Swaps | Less than 1 Year | BBB
Credit Derivatives
Derivative notional amount	9,904	30,265
Protection Sold | Total Index and Basket Credit Default Swaps | Less than 1 Year | Non-investment Grade
Credit Derivatives
Derivative notional amount	24,331	25,750
Protection Sold | Total Index and Basket Credit Default Swaps | 1 - 3 Years
Credit Derivatives
Derivative notional amount	155,987	173,157
Protection Sold | Total Index and Basket Credit Default Swaps | 1 - 3 Years | AAA
Credit Derivatives
Derivative notional amount	41,296	31,124
Protection Sold | Total Index and Basket Credit Default Swaps | 1 - 3 Years | AA
Credit Derivatives
Derivative notional amount		6,512
Protection Sold | Total Index and Basket Credit Default Swaps | 1 - 3 Years | A
Credit Derivatives
Derivative notional amount	4,668	6,841
Protection Sold | Total Index and Basket Credit Default Swaps | 1 - 3 Years | BBB
Credit Derivatives
Derivative notional amount	27,045	40,575
Protection Sold | Total Index and Basket Credit Default Swaps | 1 - 3 Years | Non-investment Grade
Credit Derivatives
Derivative notional amount	82,978	88,105
Protection Sold | Total Index and Basket Credit Default Swaps | 3 - 5 Years
Credit Derivatives
Derivative notional amount	73,934	101,247
Protection Sold | Total Index and Basket Credit Default Swaps | 3 - 5 Years | AAA
Credit Derivatives
Derivative notional amount	1,663	7,265
Protection Sold | Total Index and Basket Credit Default Swaps | 3 - 5 Years | AA
Credit Derivatives
Derivative notional amount		716
Protection Sold | Total Index and Basket Credit Default Swaps | 3 - 5 Years | A
Credit Derivatives
Derivative notional amount	6,271	10,154
Protection Sold | Total Index and Basket Credit Default Swaps | 3 - 5 Years | BBB
Credit Derivatives
Derivative notional amount	49,952	60,141
Protection Sold | Total Index and Basket Credit Default Swaps | 3 - 5 Years | Non-investment Grade
Credit Derivatives
Derivative notional amount	16,048	22,971
Protection Sold | Total Index and Basket Credit Default Swaps | Over 5 Years
Credit Derivatives
Derivative notional amount	55,023	22,616
Protection Sold | Total Index and Basket Credit Default Swaps | Over 5 Years | AAA
Credit Derivatives
Derivative notional amount	0	1,883
Protection Sold | Total Index and Basket Credit Default Swaps | Over 5 Years | AA
Credit Derivatives
Derivative notional amount		2,864
Protection Sold | Total Index and Basket Credit Default Swaps | Over 5 Years | A
Credit Derivatives
Derivative notional amount	12	30
Protection Sold | Total Index and Basket Credit Default Swaps | Over 5 Years | BBB
Credit Derivatives
Derivative notional amount	34,893	7,730
Protection Sold | Total Index and Basket Credit Default Swaps | Over 5 Years | Non-investment Grade
Credit Derivatives
Derivative notional amount	20,118	10,109
Protection Sold | Index and Basket Credit Default Swaps
Credit Derivatives
Derivative notional amount	264,416	276,465
Credit risk derivative (assets) / liability, fair value	(148)	(1,777)
Protection Sold | Tranched Index and Basket Credit Default Swaps
Credit Derivatives
Derivative notional amount	74,353	96,182
Credit risk derivative (assets) / liability, fair value	(1,394)	(2,355)
Protection Sold | Single Name, and Non-tranched Index and Basket Credit Default Swaps
Credit Derivatives
Derivative notional amount	721,000	805,000
Protection Sold | Other Credit Contracts
Credit Derivatives
Derivative notional amount	1,196	1,211
Credit risk derivative (assets) / liability, fair value	(1,042)	(500)
Protection Sold | Other Credit Contracts | Less than 1 Year
Credit Derivatives
Derivative notional amount	1	51
Protection Sold | Other Credit Contracts | 1 - 3 Years
Credit Derivatives
Derivative notional amount	806	539
Protection Sold | Other Credit Contracts | 3 - 5 Years
Credit Derivatives
Derivative notional amount	340	1
Protection Sold | Other Credit Contracts | Over 5 Years
Credit Derivatives
Derivative notional amount	49	620
Protection Purchased | Credit Default Swaps
Credit Derivatives
Derivative notional amount	841,491	934,004
Credit risk derivative (assets) / liability, fair value	162	6,538
Protection Purchased | Single Name Credit Default Swaps
Credit Derivatives
Derivative notional amount	439,328	509,872
Credit risk derivative (assets) / liability, fair value	(593)	1,641
Protection Purchased | Index and Basket Credit Default Swaps
Credit Derivatives
Derivative notional amount	231,528	229,789
Credit risk derivative (assets) / liability, fair value	(68)	1,563
Protection Purchased | Tranched Index and Basket Credit Default Swaps
Credit Derivatives
Derivative notional amount	170,635	194,343
Credit risk derivative (assets) / liability, fair value	823	3,334
Protection Purchased | Single Name, and Non-tranched Index and Basket Credit Default Swaps
Credit Derivatives
Derivative notional amount	$ 668,000	$ 731,000