Advances (Borrowers Holding Five Percent or more of Total Advances) (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Federal Home Loan Bank, Advances [Line Items]
Federal Home Loan Bank, Advances, Par Value	$ 71,112,480	$ 69,907,021
Federal Home Loan Bank Borrower Advances, Five Percent Or More Of Principal Balance [Member]
Federal Home Loan Bank, Advances [Line Items]
Federal Home Loan Bank, Advances, Par Value	$ 41,000,000	$ 40,863,000
Concentration Risk, Percentage, Five Percent or More Of Principal Balance	58.00%	58.00%
JPMorgan Chase Bank National Association [Member] | Federal Home Loan Bank Borrower Advances, Five Percent Or More Of Principal Balance [Member]
Federal Home Loan Bank, Advances [Line Items]
Federal Home Loan Bank, Advances, Par Value	$ 26,850,000	$ 32,300,000
Concentration Risk, Percentage, Five Percent or More Of Principal Balance	38.00%	46.00%
U.S. Bank, N.A. [Member] | Federal Home Loan Bank Borrower Advances, Five Percent Or More Of Principal Balance [Member]
Federal Home Loan Bank, Advances [Line Items]
Federal Home Loan Bank, Advances, Par Value	$ 9,783,000	$ 8,563,000
Concentration Risk, Percentage, Five Percent or More Of Principal Balance	14.00%	12.00%
Fifth Third Bank [Member] | Federal Home Loan Bank Borrower Advances, Five Percent Or More Of Principal Balance [Member]
Federal Home Loan Bank, Advances [Line Items]
Federal Home Loan Bank, Advances, Par Value	$ 4,367,000
Concentration Risk, Percentage, Five Percent or More Of Principal Balance	6.00%