Fair Value (Tables)

3 Months Ended

Mar. 31, 2018

Fair Value Disclosures [Abstract]

Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis

	Fair Value Measurements on a Recurring Basis
	As of March 31, 2018
(In millions)	Quoted Market Prices in Active Markets (Level 1)		Pricing Methods with Significant Observable Market Inputs (Level 2)		Pricing Methods with Significant Unobservable Market Inputs (Level 3)		Impact of Netting(1)			Total Net Carrying Value in Consolidated Statement of Condition
Assets:
Trading account assets:
U.S. government securities	$	39	$	—	$	—				$	39
Non-U.S. government securities	399		141		—					540
Other	43		556		—					599
Total trading account assets	481		697		—					1,178
AFS investment securities:
U.S. Treasury and federal agencies:
Direct obligations	11		78		—					89
Mortgage-backed securities	—		10,290		—					10,290
Total U.S. Treasury and federal agencies	11		10,368		—					10,379
Asset-backed securities:
Student loans	—		1,743		—					1,743
Credit cards	—		1,431		—					1,431
CLOs	—		—		826					826
Total asset-backed securities	—		3,174		826					4,000
Non-U.S. debt securities:
Mortgage-backed securities	—		2,952		—					2,952
Asset-backed securities	—		1,361		272					1,633
Government securities	—		10,875		—					10,875
Other(2)	—		4,353		178					4,531
Total non-U.S. debt securities	—		19,541		450					19,991
State and political subdivisions	—		7,270		37					7,307
Collateralized mortgage obligations	—		347		—					347
Other U.S. debt securities	—		2,280		—					2,280
Total AFS investment securities	11		42,980		1,313					44,304
Other assets:
Derivative instruments:
Foreign exchange contracts	—		11,046		3		$	(7,102	)	3,947
Interest-rate contracts	4		—		—		—			4
Other derivative contracts	1		—		—		—			1
Total derivative instruments	5		11,046		3		(7,102		)	3,952
Other	—		148		—		—			148
Total assets carried at fair value	$	497	$	54,871	$	1,316	$	(7,102	)	$	49,582
Liabilities:
Accrued expenses and other liabilities:
Trading account liabilities:
Other	$	41	$	—	$	—	$	—		$	41
Derivative instruments:
Foreign exchange contracts	—		11,171		2		(7,640		)	3,533
Interest-rate contracts	—		96		—		—			96
Other derivative contracts	—		288		—		—			288
Total derivative instruments	—		11,555		2		(7,640		)	3,917
Other	—		—		—		—			—
Total liabilities carried at fair value	$	41	$	11,555	$	2	$	(7,640	)	$	3,958

⁽¹⁾ Represents counterparty netting against level 2 financial assets and liabilities where a legally enforceable master netting agreement exists between State Street and the counterparty. Netting also reflects asset and liability reductions of $777 million and $1,315 million, respectively, for cash collateral received from and provided to derivative counterparties.

⁽²⁾ As of March 31, 2018, the fair value of other non-U.S. debt securities was primarily composed of $2,193 million of covered bonds and $1,738 million of corporate bonds.

	Fair Value Measurements on a Recurring Basis
	As of December 31, 2017
(In millions)	Quoted Market Prices in Active Markets (Level 1)		Pricing Methods with Significant Observable Market Inputs (Level 2)		Pricing Methods with Significant Unobservable Market Inputs (Level 3)		Impact of Netting(1)			Total Net Carrying Value in Consolidated Statement of Condition
Assets:
Trading account assets:
U.S. government securities	$	39	$	—	$	—				$	39
Non-U.S. government securities	389		93		—					482
Other	44		528		—					572
Total trading account assets	472		621		—					1,093
AFS investment securities:
U.S. Treasury and federal agencies:
Direct obligations	11		212		—					223
Mortgage-backed securities	—		10,872		—					10,872
Total U.S. Treasury and federal agencies	11		11,084		—					11,095
Asset-backed securities:
Student loans	—		3,358		—					3,358
Credit cards	—		1,542		—					1,542
CLOs	—		89		1,358					1,447
Total asset-backed securities	—		4,989		1,358					6,347
Non-U.S. debt securities:
Mortgage-backed securities	—		6,576		119					6,695
Asset-backed securities	—		2,545		402					2,947
Government securities	—		10,721		—					10,721
Other(2)	—		5,904		204					6,108
Total non-U.S. debt securities	—		25,746		725					26,471
State and political subdivisions	—		9,108		43					9,151
Collateralized mortgage obligations	—		1,054		—					1,054
Other U.S. debt securities	—		2,560		—					2,560
U.S. equity securities	—		46		—					46
U.S. money-market mutual funds	—		397		—					397
Total AFS investment securities	11		54,984		2,126					57,121
Other assets:
Derivatives instruments:
Foreign exchange contracts	—		11,596		1		$	(7,593	)	4,004
Interest-rate contracts	8		—		—		—			8
Other derivative contracts	1		—		—		—			1
Total derivative instruments	9		11,596		1		(7,593		)	4,013
Total assets carried at fair value	$	492	$	67,201	$	2,127	$	(7,593	)	$	62,227
Liabilities:
Accrued expenses and other liabilities:
Trading account liabilities:
U.S. government securities	$	39	$	—	$	—	$	—		$	39
Derivative instruments:
Foreign exchange contracts	$	—	$	11,467	$	1	$	(5,970	)	$	5,498
Interest-rate contracts	—		100		—		—			100
Other derivative contracts	1		283		—		—			284
Total derivative instruments	1		11,850		1		(5,970		)	5,882
Total liabilities carried at fair value	$	40	$	11,850	$	1	$	(5,970	)	$	5,921

⁽¹⁾ Represents counterparty netting against level 2 financial assets and liabilities where a legally enforceable master netting agreement exists between State Street and the counterparty. Netting also reflects asset and liability reductions of $2,045 million and $422 million, respectively, for cash collateral received from and provided to derivative counterparties.

⁽²⁾ As of December 31, 2017, the fair value of other non-U.S. debt securities was primarily composed of $3,537 million of covered bonds and $1,885 million of corporate bonds.

Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation

The following tables present activity related to our level 3 financial assets during the quarters ended March 31, 2018 and 2017, respectively, including total realized and unrealized gains and losses. Transfers into and out of level 3 are reported as of the beginning of the period presented. During the quarter ended March 31, 2018, transfers into level 3 were mainly related to certain ABS, including non-U.S. debt securities. During the quarters ended March 31, 2018 and 2017, transfers out of level 3 were mainly related to certain MBS and ABS, including non-U.S. debt securities, for which fair value was measured using prices for which observable market information became available.

	Fair Value Measurements Using Significant Unobservable Inputs
	Three Months Ended March 31, 2018
	Fair Value  as of December 31, 2017		Total Realized and Unrealized Gains (Losses)						Purchases		Sales			Settlements			Transfers into Level 3		Transfers out of Level 3			Fair Value as of March 31, 2018(1)		Change in Unrealized Gains (Losses) Related to Financial Instruments Held as of March 31, 2018
(In millions)			Recorded in Revenue(1)			Recorded in Other Comprehensive Income(1)
Assets:
AFS Investment securities:
Asset-backed securities:
CLOs	$	1,358	$	1		$	(1	)	$	318	$	(636	)	$	(5	)	$	—	$	(209	)	$	826
Total asset-backed securities	1,358		1			(1		)	318		(636		)	(5		)	—		(209		)	826
Non-U.S. debt securities:
Mortgage-backed securities	119		—			—			—		—			—			—		(119		)	—
Asset-backed securities	402		—			—			110		(310		)	2			68		—			272
Government securities	—		—			—			—		—			—			—		—			—
Other	204		—			—			—		—			(26		)	—		—			178
Total non-U.S. debt securities	725		—			—			110		(310		)	(24		)	68		(119		)	450
State and political subdivisions	43		—			—			—		—			(1		)	—		(5		)	37
Total AFS investment securities	2,126		1			(1		)	428		(946		)	(30		)	68		(333		)	1,313
Other assets:
Derivative instruments:
Foreign exchange contracts	1		(2		)	—			4		—			—			—		—			3		$	(2	)
Total derivative instruments	1		(2		)	—			4		—			—			—		—			3		(2		)
Total assets carried at fair value	$	2,127	$	(1	)	$	(1	)	$	432	$	(946	)	$	(30	)	$	68	$	(333	)	$	1,316	$	(2	)

⁽¹⁾ Total realized and unrealized gains (losses) on AFS investment securities are included within gains (losses) related to investment securities, net. Total realized and unrealized gains (losses) on derivative instruments are included within trading services.

	Fair Value Measurements Using Significant Unobservable Inputs
	Three Months Ended March 31, 2017
	Fair Value as of December 31, 2016		Total Realized and Unrealized Gains (Losses)					Purchases		Sales		Settlements			Fair Value as of March 31, 2017(2)		Change in Unrealized Gains (Losses) Related to Financial Instruments Held as of March 31, 2017
(In millions)			Recorded in Revenue(1)			Recorded in Other Comprehensive Income(1)
Assets:
AFS Investment securities:
Asset-backed securities:
Student loans	$	97	$	—		$	2	$	—	$	—	$	—		$	99
CLOs	905		1			—		155		—		(290		)	771
Total asset-backed securities	1,002		1			2		155		—		(290		)	870
Non-U.S. debt securities:
Asset-backed securities	32		—			—		31		—		(4		)	59
Other	248		—			—		5		—		3			256
Total non-U.S. debt securities	280		—			—		36		—		(1		)	315
State and political subdivisions	39		—			—		—		—		—			39
Collateralized mortgage obligations	16		—			—		23		—		—			39
Total AFS investment securities	1,337		1			2		214		—		(291		)	1,263
Other assets:
Derivative instruments:
Foreign exchange contracts	8		(7		)	—		5		—		(4		)	2		$	(3	)
Total derivative instruments	8		(7		)	—		5		—		(4		)	2		(3		)
Total assets carried at fair value	$	1,345	$	(6	)	$	2	$	219	$	—	$	(295	)	$	1,265	$	(3	)

⁽¹⁾ Total realized and unrealized gains (losses) on AFS investment securities are included within gains (losses) related to investment securities, net. Total realized and unrealized gains (losses) on derivative instruments are included within trading services.

⁽²⁾ There were no transfers of assets into or out of level 3 during the three months ended March 31, 2017.

Fair Value Inputs, Assets, Quantitative Information

The following table presents quantitative information, as of the dates indicated, about the valuation techniques and significant unobservable inputs used in the valuation of our level 3 financial assets and liabilities measured at fair value on a recurring basis for which we use internally-developed pricing models. The significant unobservable inputs for our level 3 financial assets and liabilities whose fair value is measured using pricing information from non-binding broker or dealer quotes are not included in the table, as the specific inputs applied are not provided by the broker/dealer.

	Quantitative Information about Level 3 Fair Value Measurements
	Fair Value						Weighted-Average
(Dollars in millions)	As of March 31, 2018		As of December 31, 2017		Valuation Technique	Significant Unobservable Input(1)	As of March 31, 2018		As of December 31, 2017
Significant unobservable inputs readily available to State Street:
Assets:
Derivative instruments, foreign exchange contracts	$	3	$	1	Option model	Volatility	—	%	7.2	%
Total	$	3	$	1
Liabilities:
Derivative instruments, foreign exchange contracts	$	2	$	1	Option model	Volatility	—	%	7.2	%
Total	$	2	$	1

⁽¹⁾ Significant changes in these unobservable inputs would result in significant changes in fair value measurement.

Fair Value Inputs, Liabilities, Quantitative Information

The following table presents quantitative information, as of the dates indicated, about the valuation techniques and significant unobservable inputs used in the valuation of our level 3 financial assets and liabilities measured at fair value on a recurring basis for which we use internally-developed pricing models. The significant unobservable inputs for our level 3 financial assets and liabilities whose fair value is measured using pricing information from non-binding broker or dealer quotes are not included in the table, as the specific inputs applied are not provided by the broker/dealer.

	Quantitative Information about Level 3 Fair Value Measurements
	Fair Value						Weighted-Average
(Dollars in millions)	As of March 31, 2018		As of December 31, 2017		Valuation Technique	Significant Unobservable Input(1)	As of March 31, 2018		As of December 31, 2017
Significant unobservable inputs readily available to State Street:
Assets:
Derivative instruments, foreign exchange contracts	$	3	$	1	Option model	Volatility	—	%	7.2	%
Total	$	3	$	1
Liabilities:
Derivative instruments, foreign exchange contracts	$	2	$	1	Option model	Volatility	—	%	7.2	%
Total	$	2	$	1

⁽¹⁾ Significant changes in these unobservable inputs would result in significant changes in fair value measurement.

Carrying Value and Estimated Fair Value of Financial Instruments by Fair Value Hierarchy

The following tables present the reported amounts and estimated fair values of the financial assets and liabilities not carried at fair value on a recurring basis, as they would be categorized within the fair value hierarchy, as of the dates indicated.

					Fair Value Hierarchy
(In millions)	Reported Amount		Estimated Fair Value		Quoted Market Prices in Active Markets (Level 1)		Pricing Methods with Significant Observable Market Inputs (Level 2)		Pricing Methods with Significant Unobservable Market Inputs (Level 3)
March 31, 2018
Financial Assets:
Cash and due from banks	$	2,546	$	2,546	$	2,546	$	—	$	—
Interest-bearing deposits with banks	79,418		79,418		—		79,418		—
Securities purchased under resale agreements	5,136		5,136		—		5,136		—
Investment securities held-to-maturity	41,158		40,483		16,577		23,783		123
Net loans (excluding leases)(1)	28,864		28,859		—		28,813		46
Other	5,750		5,750		—		5,750		—
Financial Liabilities:
Deposits:
Non-interest-bearing	$	57,025	$	57,025	$	—	$	57,025	$	—
Interest-bearing - U.S.	55,094		55,094		—		55,094		—
Interest-bearing - non-U.S.	79,398		79,398		—		79,398		—
Securities sold under repurchase agreements	2,020		2,020		—		2,020		—
Other short-term borrowings	1,066		1,066		—		1,066		—
Long-term debt	10,944		11,170		—		10,909		261
Other	5,750		5,750		—		5,750		—

⁽¹⁾ Includes $10 million of loans classified as held-for-sale that were measured at fair value on a non-recurring basis as of March 31, 2018.

					Fair Value Hierarchy
(In millions)	Reported Amount		Estimated Fair Value		Quoted Market Prices in Active Markets (Level 1)		Pricing Methods with Significant Observable Market Inputs (Level 2)		Pricing Methods with Significant Unobservable Market Inputs (Level 3)
December 31, 2017
Financial Assets:
Cash and due from banks	$	2,107	$	2,107	$	2,107	$	—	$	—
Interest-bearing deposits with banks	67,227		67,227		—		67,227		—
Securities purchased under resale agreements	3,241		3,241		—		3,241		—
Investment securities held-to-maturity	40,458		40,255		16,814		23,318		123
Net loans (excluding leases)(1)	22,577		22,482		—		22,431		51
Financial Liabilities:
Deposits:
Non-interest-bearing	$	47,175	$	47,175	$	—	$	47,175	$	—
Interest-bearing - U.S.	50,139		50,139		—		50,139		—
Interest-bearing - non-U.S.	87,582		87,582		—		87,582		—
Securities sold under repurchase agreements	2,842		2,842		—		2,842		—
Other short-term borrowings	1,144		1,144		—		1,144		—
Long-term debt	11,620		11,919		—		11,639		280

⁽¹⁾ Includes $3 million of loans classified as held-for-sale that were measured at fair value on a non-recurring basis as of December 31, 2017.