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Loans Held for Sale, at Fair Value - Additional Information (Detail) - USD ($) | 3 Months Ended
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Mar. 31, 2018 | Mar. 31, 2017
Accounts Notes And Loans Receivable [Line Items] |  |
Maximum number of days loans held for sale are typically sold | 45 days |
Loans held for sale in nonaccrual status | $ 0 | $ 0
Recognized gain from change in fair value on loans held for sale | 15,100,000 | 2,100,000
Interest Income [Member] |  |
Accounts Notes And Loans Receivable [Line Items] |  |
Interest income on Loans held for sale | 4,700,000 | 6,500,000
Greater Than 90 Days Past Due [Member] |  |
Accounts Notes And Loans Receivable [Line Items] |  |
Loans held for sale past due | $ 0 | $ 0

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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://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 30 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=75031198&loc=d3e14172-108612 + Details
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- Definition Recorded investment in financing receivables that are on nonaccrual status as of the balance sheet date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 7 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=84173941&loc=d3e5111-111524 + Details
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- Definition Interest and fee income from mortgage loans considered to be held-for-sale. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 225 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-04.1) -URI http://asc.fasb.org/extlink&oid=6879574&loc=d3e536633-122882 + Details
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