Contingencies	12 Months Ended
Dec. 31, 2016
Commitments and Contingencies Disclosure [Abstract]
Contingencies	Contingencies Legal and Regulatory Matters: In the ordinary course of business, we and our subsidiaries are involved in disputes, litigation, and governmental or regulatory inquiries and investigations, both pending and threatened. These matters, if resolved adversely against us or settled, may result in monetary damages, fines and penalties or require changes in our business practices. The resolution or settlement of these matters is inherently difficult to predict. Based on our assessment of these pending matters, we do not believe that the amount of any judgment, settlement or other action arising from any pending matter is likely to have a material adverse effect on our consolidated financial condition. However, an adverse outcome in certain of the matters described below could have a material adverse effect on our consolidated results of operations for the period in which such matter is resolved, or an accrual is determined to be required, on our consolidated financial condition, or on our reputation. We evaluate our needs for accruals of loss contingencies related to legal proceedings on a case-by-case basis. When we have a liability that we deem probable and that we deem can be reasonably estimated as of the date of our consolidated financial statements, we accrue for our estimate of the loss. We also consider a loss probable and establish an accrual when we make, or intend to make, an offer of settlement. Once established, an accrual is subject to subsequent adjustment as a result of additional information. The resolution of proceedings and the reasonably estimable loss (or range thereof) are inherently difficult to predict, especially in the early stages of proceedings. Even if a loss is probable, due to many complex factors, such as speed of discovery and the timing of court decisions or rulings, a loss or range of loss might not be reasonably estimated until the later stages of the proceeding. As of December 31, 2016, our aggregate accruals for legal loss contingencies and regulatory matters totaled approximately $90 million (excluding amounts relating to client reimbursements in connection with errors in invoicing certain of our Investment Servicing clients, described below). To the extent that we have established accruals in our consolidated statement of condition for probable loss contingencies, such accruals may not be sufficient to cover our ultimate financial exposure associated with any settlements or judgments. We may be subject to proceedings in the future that, if adversely resolved, would have a material adverse effect on our businesses or on our future consolidated financial statements. Except where otherwise noted below, we have not established accruals with respect to the claims discussed and do not believe that potential exposure is probable and can be reasonably estimated. The following discussion provides information with respect to significant legal and regulatory matters. Foreign Exchange In 2016, we settled our previously disclosed litigation and governmental investigations regarding our FX execution service that we refer to as indirect FX. Such settlements were satisfied from the previously established reserves. Transition Management In January 2014, we entered into a settlement with the FCA, pursuant to which we paid a fine of £22.9 million (approximately $37.8 million), as a result of our having charged six clients of our U.K. transition management business during 2010 and 2011 amounts in excess of the contractual terms. The SEC and the DOJ opened separate investigations into this matter. In April 2016, the U.S. Attorney’s office in Boston charged two former employees in our transition management business with criminal fraud in connection with their alleged role in this matter, and, in May 2016, the SEC commenced a parallel civil enforcement proceeding against one of these individuals. On January 18, 2017, we announced that we had entered into a settlement agreement with the DOJ and the United States Attorney for the District of Massachusetts to resolve their investigation. Under the terms of the agreement, we, among other things, paid a fine of $32.3 million and entered into a deferred prosecution agreement. Under the deferred prosecution agreement, we agreed to retain an independent compliance consultant and compliance monitor for a term of three years (subject to extension) which will, among other things, evaluate the effectiveness of our compliance controls and business ethics and make related recommendations. As previously disclosed, we are also in discussions with the SEC Staff regarding a resolution of their investigation, and have reached an agreement in principle with the Staff of the SEC to pay a penalty of $32.3 million (equal to the fine being paid to the DOJ). Resolution of the matter is subject to completion of negotiations with the SEC Staff on other terms of the settlement, followed by review and consideration by the SEC. As of December 31, 2016 we had accrued $65 million with respect to the DOJ and the SEC investigations, which includes $23 million accrued in the fourth quarter. GovEx We are cooperating in an ongoing inquiry by the SEC relating to the GovEx electronic trading platform, which was offered and operated by State Street Global Markets, LLC from September 2009 to July 2015. The subjects of the inquiry are our communications related to volume, pricing and functionalities of the platform. We are currently engaged in discussions with the Staff of the SEC concerning a possible resolution of this matter, and have reached an agreement in principle with the Staff to pay a penalty of $3 million. Resolution of the matter is subject to completion of negotiations with the SEC Staff on other terms of the settlement, followed by review and consideration by the SEC. As of December 31, 2016, we had accrued $3 million for this matter. Federal Reserve/Massachusetts Division of Banks Written Agreement On June 1, 2015, we entered into a written agreement with the Federal Reserve and the Massachusetts Division of Banks relating to deficiencies identified in our compliance programs with the requirements of the Bank Secrecy Act, AML regulations and U.S. economic sanctions regulations promulgated by OFAC. As part of this enforcement action, we are required to, among other things, implement improvements to our compliance programs and to retain an independent firm to conduct a review of account and transaction activity covering a prior three-month period to evaluate whether any suspicious activity not previously reported should have been identified and reported in accordance with applicable regulatory requirements. To the extent deficiencies in our historical reporting are identified as a result of the transaction review or if we fail to comply with the terms of the written agreement, we may become subject to fines and other regulatory sanctions, which may have a material adverse effect on us. Invoicing Matter In December 2015, we announced a review of the manner in which we invoiced certain expenses to some of our Investment Servicing clients, primarily in the United States, during an 18-year period going back to 1998, and our determination that we had incorrectly invoiced clients for certain expenses. We informed our clients in December 2015 that we will pay to them the amounts we concluded were incorrectly invoiced to them, plus interest. We currently expect to pay at least $340 million (including interest), in connection with that review, which is ongoing. We are implementing enhancements to our billing processes, and we are reviewing the conduct of our employees and have taken appropriate steps to address conduct inconsistent with our standards, including, in some cases, termination of employment. We are also evaluating other billing practices relating to our Investment Servicing clients, including calculation of asset-based fees. We have received a purported class action demand letter alleging that our invoicing practices were unfair and deceptive under Massachusetts law. A class of customers, or particular customers, may assert that we have not paid to them all amounts incorrectly invoiced, and may seek double or treble damages under Massachusetts law. We are also responding to requests for information from, and are cooperating with investigations by, governmental authorities on these matters, including the civil and criminal divisions of the DOJ, the SEC, the Department of Labor and the Massachusetts Attorney General, which could result in significant fines or other sanctions, civil and criminal, against us. The severity of such fines or other sanctions could take into account factors such as the amount and duration of our incorrect invoicing, the government’s assessment of the conduct of our employees, as well as prior conduct such as that which resulted in our recent deferred prosecution agreement in connection with transition management services and our recent settlement of civil claims regarding our indirect foreign exchange business. Any of the foregoing could have a material adverse effect on our reputation or business, including the imposition of restrictions on the operation of our business or a reduction in client demand. Resolution of these matters could also have a material adverse effect on our consolidated results of operations for the period or periods in which such matters are resolved or an accrual is determined to be required. No accrual, other than a reserve for client reimbursement, is reflected on our consolidated statement of condition as of December 31, 2016. In April 2016, the Massachusetts Secretary of State commenced an administrative enforcement proceeding against State Street Global Markets, LLC, alleging that our conduct concerning expense invoices caused State Street Global Markets, LLC to violate state law governing the securities industry by virtue of our alleged control of State Street Global Markets, LLC. The complaint sought to impose a censure, a fine and to provide for reimbursement or other relief. In December 2016, the proceeding was concluded pursuant to an agreement with the Secretary of State. Shareholder Litigation In January 2017, a State Street shareholder filed a purported class action complaint against the Company alleging that statements made by the Company in its annual reports for the 2011-15 period regarding its internal controls and procedures were misleading due to the omission of information regarding the Transition Management and Invoicing Matters discussed above. Income Taxes: In determining our provision for income taxes, we make certain judgments and interpretations with respect to tax laws in jurisdictions in which we have business operations. Because of the complex nature of these laws, in the normal course of our business, we are subject to challenges from U.S. and non-U.S. income tax authorities regarding the amount of income taxes due. These challenges may result in adjustments to the timing or amount of taxable income or deductions or the allocation of taxable income among tax jurisdictions. We recognize a tax benefit when it is more likely than not that our position will result in a tax deduction or credit. Additional information with respect to our provision for income taxes and tax benefits, including unrecognized tax benefits, is provided in Note 22. We are presently under audit by a number of tax authorities, including the Internal Revenue Service, which completed their field audit procedures on our U.S. income tax returns for the tax years 2012 and 2013. The earliest tax year open to examination in jurisdictions where we have material operations is 2010. Management believes that we have sufficiently accrued liabilities as of December 31, 2016 for tax exposures.

Legal and Regulatory Matters:

In the ordinary course of business, we and our subsidiaries are involved in disputes, litigation, and governmental or regulatory inquiries and investigations, both pending and threatened. These matters, if resolved adversely against us or settled, may result in monetary damages, fines and penalties or require changes in our business practices. The resolution or settlement of these matters is inherently difficult to predict. Based on our assessment of these pending matters, we do not believe that the amount of any judgment, settlement or other action arising from any pending matter is likely to have a material adverse effect on our consolidated financial condition. However, an adverse outcome in certain of the matters described below could have a material adverse effect on our consolidated results of operations for the period in which such matter is resolved, or an accrual is determined to be required, on our consolidated financial condition, or on our reputation.

We evaluate our needs for accruals of loss contingencies related to legal proceedings on a case-by-case basis. When we have a liability that we deem probable and that we deem can be reasonably estimated as of the date of our consolidated financial statements, we accrue for our estimate of the loss. We also consider a loss probable and establish an accrual when we make, or intend to make, an offer of settlement. Once established, an accrual is subject to subsequent adjustment as a result of additional information. The resolution of proceedings and the reasonably estimable loss (or range thereof) are inherently difficult to predict, especially in the early stages of proceedings. Even if a loss is probable, due to many complex factors, such as speed of discovery and the timing of court decisions or rulings, a loss or range of loss might not be reasonably estimated until the later stages of the proceeding.

As of December 31, 2016, our aggregate accruals for legal loss contingencies and regulatory matters totaled approximately $90 million (excluding amounts relating to client reimbursements in connection with errors in invoicing certain of our Investment Servicing clients, described below). To the extent that we have established accruals in our consolidated statement of condition for probable loss contingencies, such accruals may not be sufficient to cover our ultimate financial exposure associated with any settlements or judgments. We may be subject to proceedings in the future that, if adversely resolved, would have a material adverse effect on our businesses or on our future consolidated financial statements. Except where otherwise noted below, we have not established accruals with respect to the claims discussed and do not believe that potential exposure is probable and can be reasonably estimated.

The following discussion provides information with respect to significant legal and regulatory matters.

Foreign Exchange

In 2016, we settled our previously disclosed litigation and governmental investigations regarding our FX execution service that we refer to as indirect FX. Such settlements were satisfied from the previously established reserves.

Transition Management

In January 2014, we entered into a settlement with the FCA, pursuant to which we paid a fine of £22.9 million (approximately $37.8 million), as a result of our having charged six clients of our U.K. transition management business during 2010 and 2011 amounts in excess of the contractual terms. The SEC and the DOJ opened separate investigations into this matter. In April 2016, the U.S. Attorney’s office in Boston charged two former employees in our transition management business with criminal fraud in connection with their alleged role in this matter, and, in May 2016, the SEC commenced a parallel civil enforcement proceeding against one of these individuals.

On January 18, 2017, we announced that we had entered into a settlement agreement with the DOJ and the United States Attorney for the District of Massachusetts to resolve their investigation. Under the terms of the agreement, we, among other things, paid a fine of $32.3 million and entered into a deferred prosecution agreement. Under the deferred prosecution agreement, we agreed to retain an independent compliance consultant and compliance monitor for a term of three years (subject to extension) which will, among other things, evaluate the effectiveness of our compliance controls and business ethics and make related recommendations.

As previously disclosed, we are also in discussions with the SEC Staff regarding a resolution of their investigation, and have reached an agreement in principle with the Staff of the SEC to pay a penalty of $32.3 million (equal to the fine being paid to the DOJ). Resolution of the matter is subject to completion of negotiations with the SEC Staff on other terms of the settlement, followed by review and consideration by the SEC.

As of December 31, 2016 we had accrued $65 million with respect to the DOJ and the SEC investigations, which includes $23 million accrued in the fourth quarter.

GovEx

We are cooperating in an ongoing inquiry by the SEC relating to the GovEx electronic trading platform, which was offered and operated by State Street Global Markets, LLC from September 2009 to July 2015. The subjects of the inquiry are our communications related to volume, pricing and functionalities of the platform. We are currently engaged in discussions with the Staff of the SEC concerning a possible resolution of this matter, and have reached an agreement in principle with the Staff to pay a penalty of $3 million. Resolution of the matter is subject to completion of negotiations with the SEC Staff on other terms of the settlement, followed by review and consideration by the SEC. As of December 31, 2016, we had accrued $3 million for this matter.

Federal Reserve/Massachusetts Division of Banks Written Agreement

On June 1, 2015, we entered into a written agreement with the Federal Reserve and the Massachusetts Division of Banks relating to deficiencies identified in our compliance programs with the requirements of the Bank Secrecy Act, AML regulations and U.S. economic sanctions regulations promulgated by OFAC. As part of this enforcement action, we are required to, among other things, implement improvements to our compliance programs and to retain an independent firm to conduct a review of account and transaction activity covering a prior three-month period to evaluate whether any suspicious activity not previously reported should have been identified and reported in accordance with applicable regulatory requirements. To the extent deficiencies in our historical reporting are identified as a result of the transaction review or if we fail to comply with the terms of the written agreement, we may become subject to fines and other regulatory sanctions, which may have a material adverse effect on us.

Invoicing Matter

In December 2015, we announced a review of the manner in which we invoiced certain expenses to some of our Investment Servicing clients, primarily in the United States, during an 18-year period going back to 1998, and our determination that we had incorrectly invoiced clients for certain expenses. We informed our clients in December 2015 that we will pay to them the amounts we concluded were incorrectly invoiced to them, plus interest. We currently expect to pay at least $340 million (including interest), in connection with that review, which is ongoing. We are implementing enhancements to our billing processes, and we are reviewing the conduct of our employees and have taken appropriate steps to address conduct inconsistent with our standards, including, in some cases, termination of employment. We are also evaluating other billing practices relating to our Investment Servicing clients, including calculation of asset-based fees.

We have received a purported class action demand letter alleging that our invoicing practices were unfair and deceptive under Massachusetts law. A class of customers, or particular customers, may assert that we have not paid to them all amounts incorrectly invoiced, and may seek double or treble damages under Massachusetts law. We are also responding to requests for information from, and are cooperating with investigations by, governmental authorities on these matters, including the civil and criminal divisions of the DOJ, the SEC, the Department of Labor and the Massachusetts Attorney General, which could result in significant fines or other sanctions, civil and criminal, against us. The severity of such fines or other sanctions could take into account factors such as the amount and duration of our incorrect invoicing, the government’s assessment of the conduct of our employees, as well as prior conduct such as that which resulted in our recent deferred prosecution agreement in connection with transition management services and our recent settlement of civil claims regarding our indirect foreign exchange business. Any of the foregoing could have a material adverse effect on our reputation or business, including the imposition of restrictions on the operation of our business or a reduction in client demand. Resolution of these matters could also have a material adverse effect on our consolidated results of operations for the period or periods in which such matters are resolved or an accrual is determined to be required. No accrual, other than a reserve for client reimbursement, is reflected on our consolidated statement of condition as of December 31, 2016.

In April 2016, the Massachusetts Secretary of State commenced an administrative enforcement proceeding against State Street Global Markets, LLC, alleging that our conduct concerning expense invoices caused State Street Global Markets, LLC to violate state law governing the securities industry by virtue of our alleged control of State Street Global Markets, LLC. The complaint sought to impose a censure, a fine and to provide for reimbursement or other relief. In December 2016, the proceeding was concluded pursuant to an agreement with the Secretary of State.

Shareholder Litigation

In January 2017, a State Street shareholder filed a purported class action complaint against the Company alleging that statements made by the Company in its annual reports for the 2011-15 period regarding its internal controls and procedures were misleading due to the omission of information regarding the Transition Management and Invoicing Matters discussed above.