Derivative Instruments - Offsetting (Details) - USD ($) $ in Millions		Mar. 31, 2016		Dec. 31, 2015
Derivative Asset [Abstract]
Derivatives subject to netting arrangements, Gross assets recognized		$ 16,713		$ 13,658
Derivatives subject to netting arrangements, Gross amounts offset in the balance sheet	[1]	13,886	[2]	11,115	[3]
Derivatives subject to netting arrangements, Net assets recognized on the balance sheet		2,827		2,543
Total derivatives, Gross amounts not offset in the balance sheet, Financial instruments		687		495
Total derivatives, Gross amounts not offset in the balance sheet, Cash collateral received		0		0
Derivative assets subject to netting arrangements, gross amounts offset in the balance sheet		2,140		2,048
Total derivatives not subject to netting arrangements		2,476		2,142
Total derivatives, Gross assets recognized	[4]	19,189		15,800
Total derivatives, Net assets recognized on the balance sheet		5,303		4,685
Total derivatives, Net amount		4,616		4,190
Reverse repurchase agreements, Gross assets recognized		20,910		17,088
Reverse repurchase agreements, Gross amounts offset in the balance sheet		1,678	[2],[5]	357	[3],[6]
Reverse repurchase agreements, Net assets recognized on the balance sheet		19,232		16,731
Reverse repurchase agreements, Gross amounts not offset in the balance sheet, Financial instruments		19,232		16,726
Reverse repurchase agreements, Gross amounts not offset in the balance sheet, Cash collateral received		0		0
Reverse repurchase agreements, Net amount		0		5
Securities borrowing, Gross assets recognized		7,657		7,630
Securities borrowing, Net assets recognized on the balance sheet		7,657		7,630
Securities borrowing, Gross amounts not offset in the balance sheet, Financial instruments		7,447		7,373
Securities borrowing, Net amount		210		257
Total, Gross assets recognized		47,756		40,518
Total, Gross amounts offset in the balance sheet		15,564	[2]	11,472	[3]
Total, Net assets recognized on the balance sheet		32,192		29,046
Total, Gross amounts not offset in the balance sheet, Financial instruments		27,366		24,594
Total, Gross amounts not offset in the balance sheet, Cash collateral received		0		0
Total, Net amount		4,826		4,452
Derivative Liability [Abstract]
Derivatives subject to netting arrangements, Gross liabilities recognized		17,562		13,742
Derivatives subject to netting arrangements, Gross amounts offset in the balance sheet	[1]	13,525	[7]	10,869	[8]
Derivatives subject to netting arrangements, Net liabilities recognized on the balance sheet		4,037		2,873
Derivatives subject to netting arrangements, Gross amounts not offset in the balance sheet, Financial instruments		2,435		2,140
Derivatives subject to netting arrangements, Gross amounts not offset in the balance sheet, Cash collateral pledged		0		0
Derivatives subject to netting arrangements, Net amount		1,602		733
Total derivatives not subject to netting arrangements		1,678		1,446
Total derivatives, Gross liabilities recognized	[4]	19,240		15,188
Total derivatives, Net liabilities recognized on the balance sheet		5,715		4,319
Total derivatives, Net amount		3,280		2,179
Repurchase agreements, Gross liabilities recognized		6,810		7,737
Repurchase agreements, Gross amounts offset in the balance sheet		1,678	[7],[9]	357	[8],[10]
Repurchase agreements, Net liabilities recognized on the balance sheet		5,132		7,380
Repurchase agreements, Gross amounts not offset in the balance sheet, Financial instruments		5,132		7,380
Repurchase agreements, Gross amounts not offset in the balance sheet, Cash collateral pledged		0		0
Repurchase agreements, Net amount		0		0
Securities lending, Gross liabilities recognized		1,488		1,801
Securities lending, Net liabilities recognized on the balance sheet		1,488		1,801
Securities lending, Gross amounts not offset in the balance sheet, Financial instruments		1,429		1,727
Securities lending, Net amount		59		74
Total, Gross liabilities recognized		27,538		24,726
Total, Gross amounts offset in the balance sheet		15,203	[7]	11,226	[8]
Total, Net liabilities recognized on the balance sheet		12,335		13,500
Total, Gross amounts not offset in the balance sheet, Financial instruments		8,996		11,247
Total, Gross amounts not offset in the balance sheet, Cash collateral pledged		0		0
Total, Net amount		3,339		2,253
Interest rate contracts
Derivative Asset [Abstract]
Derivatives subject to netting arrangements, Gross assets recognized		12,023		9,554
Derivatives subject to netting arrangements, Gross amounts offset in the balance sheet		10,343	[2]	8,071	[3]
Derivatives subject to netting arrangements, Net assets recognized on the balance sheet		1,680		1,483
Total derivatives, Gross amounts not offset in the balance sheet, Financial instruments		508		432
Total derivatives, Gross amounts not offset in the balance sheet, Cash collateral received		0		0
Derivative assets subject to netting arrangements, gross amounts offset in the balance sheet		1,172		1,051
Derivative Liability [Abstract]
Derivatives subject to netting arrangements, Gross liabilities recognized		13,001		10,188
Derivatives subject to netting arrangements, Gross amounts offset in the balance sheet		10,468	[7]	8,235	[8]
Derivatives subject to netting arrangements, Net liabilities recognized on the balance sheet		2,533		1,953
Derivatives subject to netting arrangements, Gross amounts not offset in the balance sheet, Financial instruments		2,295		1,795
Derivatives subject to netting arrangements, Gross amounts not offset in the balance sheet, Cash collateral pledged		0		0
Derivatives subject to netting arrangements, Net amount		238		158
Foreign exchange contracts
Derivative Asset [Abstract]
Derivatives subject to netting arrangements, Gross assets recognized		4,558		3,981
Derivatives subject to netting arrangements, Gross amounts offset in the balance sheet		3,484	[2]	2,981	[3]
Derivatives subject to netting arrangements, Net assets recognized on the balance sheet		1,074		1,000
Total derivatives, Gross amounts not offset in the balance sheet, Financial instruments		179		63
Total derivatives, Gross amounts not offset in the balance sheet, Cash collateral received		0		0
Derivative assets subject to netting arrangements, gross amounts offset in the balance sheet		895		937
Derivative Liability [Abstract]
Derivatives subject to netting arrangements, Gross liabilities recognized		4,437		3,409
Derivatives subject to netting arrangements, Gross amounts offset in the balance sheet		2,997	[7]	2,567	[8]
Derivatives subject to netting arrangements, Net liabilities recognized on the balance sheet		1,440		842
Derivatives subject to netting arrangements, Gross amounts not offset in the balance sheet, Financial instruments		79		274
Derivatives subject to netting arrangements, Gross amounts not offset in the balance sheet, Cash collateral pledged		0		0
Derivatives subject to netting arrangements, Net amount		1,361		568
Equity contracts
Derivative Asset [Abstract]
Derivatives subject to netting arrangements, Gross assets recognized		132		123
Derivatives subject to netting arrangements, Gross amounts offset in the balance sheet		59	[2]	63	[3]
Derivatives subject to netting arrangements, Net assets recognized on the balance sheet		73		60
Total derivatives, Gross amounts not offset in the balance sheet, Financial instruments		0		0
Total derivatives, Gross amounts not offset in the balance sheet, Cash collateral received		0		0
Derivative assets subject to netting arrangements, gross amounts offset in the balance sheet		73		60
Derivative Liability [Abstract]
Derivatives subject to netting arrangements, Gross liabilities recognized		124		145
Derivatives subject to netting arrangements, Gross amounts offset in the balance sheet		60	[7]	67	[8]
Derivatives subject to netting arrangements, Net liabilities recognized on the balance sheet		64		78
Derivatives subject to netting arrangements, Gross amounts not offset in the balance sheet, Financial instruments		61		71
Derivatives subject to netting arrangements, Gross amounts not offset in the balance sheet, Cash collateral pledged		0		0
Derivatives subject to netting arrangements, Net amount		$ 3		$ 7

[1] Effect of master netting agreements includes cash collateral received and paid of $896 million and $535 million, respectively, at March 31, 2016, and $792 million and $546 million, respectively, at Dec. 31, 2015.

[2] Includes the effect of netting agreements and net cash collateral received. The offset related to the over-the-counter derivatives was allocated to the various types of derivatives based on the net positions.

[3] Includes the effect of netting agreements and net cash collateral received. The offset related to the over-the-counter derivatives was allocated to the various types of derivatives based on the net positions.

[4] Fair values are on a gross basis, before consideration of master netting agreements, as required by ASC 815.

[5] Offsetting of reverse repurchase agreements relates to our involvement in the Fixed Income Clearing Corporation, where we settle government securities transactions on a net basis for payment and delivery through the Fedwire system.

[6] Offsetting of reverse repurchase agreements relates to our involvement in the Fixed Income Clearing Corporation, where we settle government securities transactions on a net basis for payment and delivery through the Fedwire system.

[7] Includes the effect of netting agreements and net cash collateral paid. The offset related to the over-the-counter derivatives was allocated to the various types of derivatives based on the net positions.

[8] Includes the effect of netting agreements and net cash collateral paid. The offset related to the over-the-counter derivatives was allocated to the various types of derivatives based on the net positions.

[9] Offsetting of repurchase agreements relates to our involvement in the Fixed Income Clearing Corporation, where we settle government securities transactions on a net basis for payment and delivery through the Fedwire system.

[10] Offsetting of repurchase agreements relates to our involvement in the Fixed Income Clearing Corporation, where we settle government securities transactions on a net basis for payment and delivery through the Fedwire system.