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Covered Loans Acquired in Acquisitions of AmTrust Bank ("Am Trust") and Desert Hills Bank ("Desert Hills") (Detail) - USD ($) $ in Thousands | Mar. 31, 2017 | Dec. 31, 2016
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Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Covered loans | $ 1,599,101 | $ 1,698,133
Percent of Covered Loans | 100.00% |
One-to-four family |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Covered loans | $ 1,531,872 |
Percent of Covered Loans | 95.80% |
Other loans |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Covered loans | $ 67,229 |
Percent of Covered Loans | 4.20% |

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- Definition Percentage of Covered Loans + References No definition available. + Details
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Balance Type: | na
Period Type: | instant

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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. + Details
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Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
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- Definition Aggregate gross carrying amount of loans and leases receivable covered by loss sharing agreements. + References No definition available. + Details
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Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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- Details
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Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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- Details
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Namespace Prefix: |
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Balance Type: |
Period Type: |