Variable Interest Entities	9 Months Ended
Sep. 30, 2013
Variable Interest Entities [Abstract]
Variable Interest Entities	Variable Interest Entities Asset-Backed Investment Securities: We invest in various forms of asset-backed securities, which we carry in our investment securities portfolio. These asset-backed securities meet the GAAP definition of asset securitization entities, which are considered to be VIEs as defined by GAAP. We are not considered to be the primary beneficiary of these VIEs, as defined by GAAP, since we do not have control over their activities. Additional information about our asset-backed securities is provided in note 3. Tax-Exempt Investment Program: In the normal course of our business, we structure and sell certificated interests in pools of tax-exempt investment-grade assets, principally to our mutual fund clients. We structure these pools as partnership trusts, and the assets and liabilities of the trusts are recorded in our consolidated statement of condition as investment securities available for sale and other short-term borrowings. We may also provide liquidity and re-marketing services to the trusts. As of September 30, 2013 and December 31, 2012, we carried investment securities available for sale, composed of securities related to state and political subdivisions, with a fair value of $2.38 billion and $2.68 billion, respectively, and other short-term borrowings of $1.98 billion and $2.15 billion, respectively, in our consolidated statement of condition in connection with these trusts. We transfer assets to the trusts from our investment securities portfolio at adjusted book value, and the trusts finance the acquisition of these assets by selling certificated interests issued by the trusts to third-party investors and to State Street as residual holder. These transfers do not meet the de-recognition criteria defined by GAAP, and therefore, are recorded in our consolidated financial statements. The trusts had a weighted-average life of approximately 6.7 years as of September 30, 2013, compared to approximately 6.9 years as of December 31, 2012. Under separate legal agreements, we provide standby bond-purchase agreements to these trusts and, with respect to certain securities, letters of credit. Our commitments to the trusts under these standby bond-purchase agreements and letters of credit totaled $2.02 billion and $691 million, respectively, as of September 30, 2013, none of which was utilized at period-end. In the event that our obligations under these agreements are triggered, no material impact to our consolidated results of operations or financial condition is expected to occur, because the securities are already recorded at fair value in our consolidated statement of condition. Interests in Sponsored Investment Funds: In the normal course of business, we manage various types of sponsored investment funds through SSgA. The services we provide to these sponsored investment funds generate management fee revenue. From time to time, we may invest cash in the funds, which we refer to as seed capital, in order for the funds to establish a performance history for newly-launched strategies. These funds may be considered VIEs. As of September 30, 2013, we have not been deemed to be the primary beneficiary of these funds, and as a result have not included the funds in our consolidated financial statements. Our potential maximum loss exposure associated with our investments in these unconsolidated funds totaled $18 million and $28 million as of September 30, 2013 and December 31, 2012, respectively, and represented the carrying value of our seed capital investment, which is recorded in either investment securities available for sale or other assets in our consolidated statement of condition. The amount of loss we may recognize in any period is limited to the carrying amount of our seed capital investment in the unconsolidated fund.

Variable Interest Entities

Asset-Backed Investment Securities:

We invest in various forms of asset-backed securities, which we carry in our investment securities portfolio. These asset-backed securities meet the GAAP definition of asset securitization entities, which are considered to be VIEs as defined by GAAP. We are not considered to be the primary beneficiary of these VIEs, as defined by GAAP, since we do not have control over their activities. Additional information about our asset-backed securities is provided in note 3.

Tax-Exempt Investment Program:

In the normal course of our business, we structure and sell certificated interests in pools of tax-exempt investment-grade assets, principally to our mutual fund clients. We structure these pools as partnership trusts, and the assets and liabilities of the trusts are recorded in our consolidated statement of condition as investment securities available for sale and other short-term borrowings. We may also provide liquidity and re-marketing services to the trusts. As of September 30, 2013 and December 31, 2012, we carried investment securities available for sale, composed of securities related to state and political subdivisions, with a fair value of $2.38 billion and $2.68 billion, respectively, and other short-term borrowings of $1.98 billion and $2.15 billion, respectively, in our consolidated statement of condition in connection with these trusts.

We transfer assets to the trusts from our investment securities portfolio at adjusted book value, and the trusts finance the acquisition of these assets by selling certificated interests issued by the trusts to third-party investors and to State Street as residual holder. These transfers do not meet the de-recognition criteria defined by GAAP, and therefore, are recorded in our consolidated financial statements. The trusts had a weighted-average life of approximately 6.7 years as of September 30, 2013, compared to approximately 6.9 years as of December 31, 2012.

Under separate legal agreements, we provide standby bond-purchase agreements to these trusts and, with respect to certain securities, letters of credit. Our commitments to the trusts under these standby bond-purchase agreements and letters of credit totaled $2.02 billion and $691 million, respectively, as of September 30, 2013, none of which was utilized at period-end. In the event that our obligations under these agreements are triggered, no material impact to our consolidated results of operations or financial condition is expected to occur, because the securities are already recorded at fair value in our consolidated statement of condition.

Interests in Sponsored Investment Funds:

In the normal course of business, we manage various types of sponsored investment funds through SSgA. The services we provide to these sponsored investment funds generate management fee revenue. From time to time, we may invest cash in the funds, which we refer to as seed capital, in order for the funds to establish a performance history for newly-launched strategies. These funds may be considered VIEs. As of September 30, 2013, we have not been deemed to be the primary beneficiary of these funds, and as a result have not included the funds in our consolidated financial statements.

Our potential maximum loss exposure associated with our investments in these unconsolidated funds totaled $18 million and $28 million as of September 30, 2013 and December 31, 2012, respectively, and represented the carrying value of our seed capital investment, which is recorded in either investment securities available for sale or other assets in our consolidated statement of condition. The amount of loss we may recognize in any period is limited to the carrying amount of our seed capital investment in the unconsolidated fund.