Borrowings (FHLB Advances) (Details) - USD ($) $ in Millions	Jun. 30, 2017	Dec. 31, 2016
Federal Home Loan Bank, Advances, Branch of FHLB Bank [Line Items]
Short term debt FHLB advances and other	$ 3,670	$ 1,780
Current portion of fixed rate advances	1,200	1,200
Federal Home Loan Bank Advances	4,870	2,980
Long-term fixed rate advances
Federal Home Loan Bank, Advances, Branch of FHLB Bank [Line Items]
Current portion of fixed rate advances	175	50
Short-term adjustable rate
Federal Home Loan Bank, Advances, Branch of FHLB Bank [Line Items]
Short term debt FHLB advances and other	$ 3,670	$ 1,780
Federal Home Loan Bank Advances, Rate (as a percent)	1.14%	0.62%
Long-term LIBOR adjustable advances
Federal Home Loan Bank, Advances, Branch of FHLB Bank [Line Items]
Federal Home Loan Bank Advances, Rate (as a percent)	1.41%	1.12%
Current portion of fixed rate advances	$ 1,025	$ 1,025
Long-term fixed rate advances
Federal Home Loan Bank, Advances, Branch of FHLB Bank [Line Items]
Federal Home Loan Bank Advances, Rate (as a percent)	1.12%	1.12%
Current portion of fixed rate advances	$ 175	$ 175

Amount of borrowings as of the balance sheet date from the Federal Home Loan Bank, which are primarily used to cover shortages in the required reserve balance and liquidity shortages.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 470
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6479118&loc=d3e64650-112822

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The current portion of Federal Home Loan Bank borrowings initially due beyond one year or beyond the normal operating cycle if longer.

+ References

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States the interest rate applicable to Federal Home Loan Bank advances outstanding as of the Balance Sheet date.

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-Publisher FASB
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Including both current and noncurrent portions, Federal Home Loan Bank borrowings initially due beyond one year or beyond the normal operating cycle if longer.

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