Guarantees, Pledged Assets and Collateral Guarantees, Collateral Type and Contractual Maturities of Repurchase Agreements and Securities Lending Agreements (Details) $ in Millions	Jun. 30, 2015 USD ($)
Secured Borrowings, Gross Including Not Subject to Master Netting Arrangement [Abstract]
Repurchase Agreements	$ 73,513
Securities Lending	9,890
Total Repurchases and Securities Lending	83,403
Securities of U.S. Treasury and federal agencies [Member]
Secured Borrowings, Gross Including Not Subject to Master Netting Arrangement [Abstract]
Repurchase Agreements	27,724
Securities Lending	103
Securities of U.S. states and political subdivisions [Member]
Secured Borrowings, Gross Including Not Subject to Master Netting Arrangement [Abstract]
Repurchase Agreements	77
Federal agencies [Member]
Secured Borrowings, Gross Including Not Subject to Master Netting Arrangement [Abstract]
Repurchase Agreements	35,139
Securities Lending	52
Non-Agency Mortgage-backed Securities [Member]
Secured Borrowings, Gross Including Not Subject to Master Netting Arrangement [Abstract]
Repurchase Agreements	2,053
Corporate debt securities [Member]
Secured Borrowings, Gross Including Not Subject to Master Netting Arrangement [Abstract]
Repurchase Agreements	4,963
Securities Lending	752
Asset-backed Securities [Member]
Secured Borrowings, Gross Including Not Subject to Master Netting Arrangement [Abstract]
Repurchase Agreements	2,502
Equity Securities [Member]
Secured Borrowings, Gross Including Not Subject to Master Netting Arrangement [Abstract]
Repurchase Agreements	707
Securities Lending	8,983
Other [Member]
Secured Borrowings, Gross Including Not Subject to Master Netting Arrangement [Abstract]
Repurchase Agreements	348
Overnight/Continuous [Member]
Secured Borrowings, Gross Including Not Subject to Master Netting Arrangement [Abstract]
Repurchase Agreements	47,667
Securities Lending	8,865
Total Repurchases and Securities Lending	56,532
Up to 30 days [Member]
Secured Borrowings, Gross Including Not Subject to Master Netting Arrangement [Abstract]
Repurchase Agreements	19,169
Securities Lending	753
Total Repurchases and Securities Lending	19,922
30-90 days [Member]
Secured Borrowings, Gross Including Not Subject to Master Netting Arrangement [Abstract]
Repurchase Agreements	5,902
Securities Lending	272
Total Repurchases and Securities Lending	6,174
Over 90 days [Member]
Secured Borrowings, Gross Including Not Subject to Master Netting Arrangement [Abstract]
Repurchase Agreements	775
Securities Lending	0
Total Repurchases and Securities Lending	$ 775