Loans Receivable and Allowance for Credit Losses (Composition of Non-PCI and PCI Loans - Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2018	Dec. 31, 2017
LOANS RECEIVABLE AND ALLOWANCE FOR LOAN LOSSES
Loans held-for-investment pledged as collateral	$ 19,495,480	$ 18,880,598
Minimum
LOANS RECEIVABLE AND ALLOWANCE FOR LOAN LOSSES
Adjustable rate mortgage, initial fixed periods	1 year
Maximum
LOANS RECEIVABLE AND ALLOWANCE FOR LOAN LOSSES
Adjustable rate mortgage, initial fixed periods	7 years
Consumer lending \| Home equity lines of credit (“HELOCs”)
LOANS RECEIVABLE AND ALLOWANCE FOR LOAN LOSSES
Loan-to-value ratio (or less at origination)	60.00%

The term of the initial fixed interest rate period of an adjustable rate mortgage loan.

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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.

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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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

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