Fair Value - Fair Value Measurement (Detail) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
Mar. 31, 2020	Dec. 31, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assumed Gain/(Loss) From Loan Sale	$ 6,966
Interest Rate Movement Effect	23,498
Servicing Rights Value	23
Security Price Change	(27,097)
Total Fair Value Measurement Gain/(Loss)	3,390	$ 14,111
Mortgage Banking [Member] \| Level 2 [Member] \| Fair Value, Recurring [Member] \| Rate Lock Commitments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value Disclosure, Off-balance Sheet Risks, Face Amount, Liability	972,380
Assumed Gain/(Loss) From Loan Sale	3,137
Interest Rate Movement Effect	15,723
Servicing Rights Value	170
Total Fair Value Measurement Gain/(Loss)	19,030
Mortgage Banking [Member] \| Level 2 [Member] \| Fair Value, Recurring [Member] \| Forward Sales Contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value Disclosure, Off-balance Sheet Risks, Face Amount, Liability	1,293,045
Security Price Change	(27,097)
Total Fair Value Measurement Gain/(Loss)	(27,097)
Mortgage Banking [Member] \| Level 2 [Member] \| Fair Value, Recurring [Member] \| Mortgages Held for Sale [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assumed Gain/(Loss) From Loan Sale	3,829
Interest Rate Movement Effect	7,775
Servicing Rights Value	(147)
Fair Value, Option, Changes in Fair Value, Gain (Loss)	11,457	7,019
Fair Value, Principal Amount, Loans Held for Sale	$ 419,485	$ 485,106

Fair value measurement assumed gain (loss) from loan sale.

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Fair value measurement changes attributable to servicing rights value changes.

+ References

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- Definition

Interest rate movement effect on fair value measurement.

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Security price change effect on fair value measurement.

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- Definition

Fair Value, Principal Amount, Loans Held for Sale

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- Definition

Amount of realized and unrealized gain (loss) of derivative instruments not designated or qualifying as hedging instruments.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4CC
-URI http://asc.fasb.org/extlink&oid=109980867&loc=SL109998890-113959

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
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-Section 50
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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.

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- Definition

The face amount of financial liabilities, which are not recognized in the financial statements (off-balance sheet) because they fail to meet some other criterion for recognition.

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- Definition

For each line item in the statement of financial position, the amounts of gains and losses from fair value changes included in earnings.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 30
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