Quarterly report pursuant to Section 13 or 15(d)

Schedule of Underlying Assets of Federal Home Loan Bank Advances (Details)

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Schedule of Underlying Assets of Federal Home Loan Bank Advances (Details) - USD ($)
$ in Thousands
Sep. 30, 2017
Dec. 31, 2016
Schedule of Assets Underlying Federal Home Loan Bank Advances [Line Items]    
Assets pledged as collateral for Federal Home Loan Bank advances $ 2,084,590 $ 4,287,485
Federal Home Loan Bank stock 85,175 167,856
Federal Home Loan Bank of Des Moines [Member]    
Schedule of Assets Underlying Federal Home Loan Bank Advances [Line Items]    
Federal Home Loan Bank stock 85,176 167,856
Available-for-sale Securities [Member]    
Schedule of Assets Underlying Federal Home Loan Bank Advances [Line Items]    
Assets pledged as collateral for Federal Home Loan Bank advances 2,048,924 3,576,481
Commercial Real Estate Assets [Member]    
Schedule of Assets Underlying Federal Home Loan Bank Advances [Line Items]    
Assets pledged as collateral for Federal Home Loan Bank advances 33,626 708,989
Retained Interest [Member]    
Schedule of Assets Underlying Federal Home Loan Bank Advances [Line Items]    
Assets pledged as collateral for Federal Home Loan Bank advances $ 2,040 $ 2,015