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Loans Receivable and Allowance for Credit Losses (Composition of Non-PCI and PCI Loans- Narrative) (Details) - USD ($) $ in Thousands | 12 Months Ended |
--- | --- | ---
Dec. 31, 2017 | Dec. 31, 2016
LOANS RECEIVABLE AND ALLOWANCE FOR LOAN LOSSES |  |
Loans receivable pledged to secure borrowings and to provide additional borrowing capacity from the FHLB and the Federal Reserve Bank | $ 18,880,598 | $ 16,441,068
Residential | Minimum |  |
LOANS RECEIVABLE AND ALLOWANCE FOR LOAN LOSSES |  |
Adjustable rate mortgage, initial fixed periods | 1 year |
Residential | Maximum |  |
LOANS RECEIVABLE AND ALLOWANCE FOR LOAN LOSSES |  |
Adjustable rate mortgage, initial fixed periods | 7 years |
Consumer Lending | HELOCs |  |
LOANS RECEIVABLE AND ALLOWANCE FOR LOAN LOSSES |  |
Loan to value ratio | 60.00% |

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- Definition Ratio which compares the amount of the borrower’s first mortgage with the appraised value of the property. It is computed as Current Loan Balance ÷ Current Appraised Value + References No definition available. + Details
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- Definition Carrying amount as of the balance sheet date of loans that have been pledged as collateral for borrowings. If the secured party has the right by contract or custom to sell or re-pledge the collateral, then the debtor reclassifies that asset and report that asset in its statement of financial position separately from other assets not so encumbered. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 860 -SubTopic 30 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=66007379&loc=d3e113888-111728 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=84173941&loc=d3e5086-111524 + Details
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