Line of Business Information - Summary of Line of Business (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2018	Mar. 31, 2017
Segment Reporting Information [Line Items]
Servicing fees	$ 1,421	$ 1,296
Management fees	472	382
Trading services	304	275
Securities finance	141	133
Processing fees and other	25	112
Total fee revenue	2,363	2,198
Net interest income	658	510
Gains (losses) related to investment securities, net	(2)	(40)
Total revenue	3,019	2,668
Provision for loan losses	0	(2)
Total expenses	2,256	2,086
Income before income tax expense (benefit)	$ 763	$ 584
Pre-tax margin	25.00%	22.00%
Investment Servicing
Segment Reporting Information [Line Items]
Total revenue	$ 2,522
Investment Management
Segment Reporting Information [Line Items]
Total revenue	497
Operating Segments \| Investment Servicing
Segment Reporting Information [Line Items]
Servicing fees	1,421	$ 1,296
Management fees	0	0
Trading services	274	257
Securities finance	141	133
Processing fees and other	25	106
Total fee revenue	1,861	1,792
Net interest income	663	509
Gains (losses) related to investment securities, net	(2)	(40)
Total revenue	2,522	2,261
Provision for loan losses	0	(2)
Total expenses	1,858	1,728
Income before income tax expense (benefit)	$ 664	$ 535
Pre-tax margin	26.00%	24.00%
Operating Segments \| Investment Management
Segment Reporting Information [Line Items]
Servicing fees	$ 0	$ 0
Management fees	472	382
Trading services	30	18
Securities finance	0	0
Processing fees and other	0	6
Total fee revenue	502	406
Net interest income	(5)	1
Gains (losses) related to investment securities, net	0	0
Total revenue	497	407
Provision for loan losses	0	0
Total expenses	398	329
Income before income tax expense (benefit)	$ 99	$ 78
Pre-tax margin	20.00%	19.00%
Other
Segment Reporting Information [Line Items]
Servicing fees	$ 0	$ 0
Management fees	0	0
Trading services	0	0
Securities finance	0	0
Processing fees and other	0	0
Total fee revenue	0	0
Net interest income	0	0
Gains (losses) related to investment securities, net	0	0
Total revenue	0	0
Provision for loan losses	0	0
Total expenses	0	29
Income before income tax expense (benefit)	$ 0	$ (29)

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Trading Services Revenue

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Income from services rendered by trust departments or by any consolidated subsidiaries acting in a fiduciary capacity, including fees earned for (1) acting as an agent for fiduciary placement and loans and (2) custody or investment advisory services when such fees are not separately billed to the customer. This item excludes commissions and fees received for the accumulation or disbursement of funds deposited to Individual Retirement or Keogh plan accounts when such are not handled by the reporting entity's trust department.

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Amount of fee and commission revenue classified as other.

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Amount of income (loss) from continuing operations before deduction of income tax expense (benefit) and income (loss) attributable to noncontrolling interest, and addition of income (loss) from equity method investments.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(h)(1)(i))
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The net amount of operating interest income (expense).

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Amount of revenue from providing investment advisory, asset management and administrative services, including, but not limited to, distribution and shareholder services, accounting, tax, legal, regulatory filing, share registration, and shareholder correspondence activities.

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Amount of fees and commissions from banking, advisory, brokerage, and securities underwriting activities. Activities include, but are not limited to, underwriting securities, private placements of securities, investment advisory and management services, merger and acquisition services, sale and servicing of mutual funds, and other related consulting fees.

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This item represents the net total realized and unrealized gain (loss) included in earnings for the period as a result of selling or holding marketable securities categorized as trading, available-for-sale, or held-to-maturity, including the unrealized holding gain (loss) of held-to-maturity securities transferred to the trading security category and the cumulative unrealized gain (loss) which was included in other comprehensive income (a separate component of shareholders' equity) for available-for-sale securities transferred to trading securities during the period. Additionally, this item would include any losses recognized for other than temporary impairments (OTTI) of the subject investments in debt and equity securities.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 9
-Subparagraph (a),(c)-(e)
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-Name Accounting Standards Codification
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Total aggregate amount of all noninterest expense.

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The total amount of noninterest income which may be derived from: (1) fees and commissions; (2) premiums earned; (3) insurance policy charges; (4) the sale or disposal of assets; and (5) other sources not otherwise specified.

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Amount of expense related to estimated loss from loan and lease transactions.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 225
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04.11)
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Amount of revenue recognized from goods sold, services rendered, insurance premiums, or other activities that constitute an earning process. Includes, but is not limited to, investment and interest income before deduction of interest expense when recognized as a component of revenue, and sales and trading gain (loss).

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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