Loans Receivable and Allowance for Credit Losses (Composition of Non-PCI and PCI Loans - Narrative) (Details) $ in Thousands	3 Months Ended
Mar. 31, 2019 USD ($) property_unit	Dec. 31, 2018 USD ($)
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 \| $	$ 20,952,709	$ 20,590,035
Consumer lending \| Single-family residential and home equity line of credit
LOANS RECEIVABLE AND ALLOWANCE FOR LOAN LOSSES
Loan-to-value ratio (or less at origination)	60.00%
Multifamily residential \| Commercial lending \| Minimum
LOANS RECEIVABLE AND ALLOWANCE FOR LOAN LOSSES
Number of units in multifamily properties used to secure multifamily residential loans	5
Multifamily residential \| Commercial lending \| Maximum
LOANS RECEIVABLE AND ALLOWANCE FOR LOAN LOSSES
Number of units in multifamily properties used to secure multifamily residential loans	15

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

No definition available.

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- Definition

Number of Units in the Multifamily Properties Used as Collateral

+ 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://fasb.org/us-gaap/role/ref/legacyRef
-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://fasb.org/us-gaap/role/ref/legacyRef
-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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