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Derivative Financial Instruments (Narrative) (Detail) - USD ($) | 1 Months Ended | 12 Months Ended |
--- | --- | --- | ---
Oct. 31, 2007 | Dec. 31, 2016 | Dec. 31, 2015 | Dec. 31, 2014 | Dec. 31, 2007
Derivative [Line Items] |  |  |  |  |
Weighted-average strike rate for outstanding interest rate caps |  | 2.87% |  |  |
Approximate credit exposure related to swaps with bank customers |  | $ 31,000,000 |  |  |
Aggregate fair value of securities posted as collateral for derivative contracts |  | 21,700,000 |  |  |
Cash collateral on deposit with other financial institutions |  | 14,700,000 | $ 16,900,000 |  |
Variable-Rate Loans Outstanding [Member] |  |  |  |  |
Derivative [Line Items] |  |  |  |  |
Number of Interest Rate Derivatives Held |  |  |  |  | 3
Notional amount of interest rate swap contracts |  |  |  |  | $ 1,200,000,000
Principal amount outstanding of variable-rate loans |  |  |  |  | $ 1,200,000,000
Period for which cash flow hedges were used to hedge monthly interest receipts | 84 months |  |  |  |
Interest Rate Swaps With Upstream Financial Institution Counterparties [Member] |  |  |  |  |
Derivative [Line Items] |  |  |  |  |
Approximate credit exposure related to swaps with bank customers |  | 9,200,000 |  |  |
Designated as Hedging Instrument [Member] | Interest Income [Member] | Variable-Rate Loans Outstanding [Member] |  |  |  |  |
Derivative [Line Items] |  |  |  |  |
Gain (Loss) on Cash Flow Hedge Ineffectiveness, Net |  | $ 0 | $ 0 | $ 0 |

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- Definition Aggregate notional amount specified by the derivative(s). Expressed as an absolute value. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Article 12 -Section 13 -Sentence Column B + Details
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- Definition Carrying amount as of the balance sheet date of cash collateral held for borrowed securities, for which the cash is restricted as to withdrawal or usage. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03.1) -URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03.(a),2) -URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910 + Details
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- Definition Maximum potential amount of future undiscounted payments that could be required under the credit derivative, before reduction for potential recoveries under recourse or collateralization provisions. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4K -Subparagraph (b)(1) -URI http://asc.fasb.org/extlink&oid=64837297&loc=SL5708775-113959 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Credit Derivative -URI http://asc.fasb.org/extlink&oid=6854095 + Details
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- Definition The net gain (loss) recognized in earnings during the reporting period representing the amount of the cash flow hedges' ineffectiveness. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4C -Subparagraph (d)(1) -URI http://asc.fasb.org/extlink&oid=64837297&loc=SL5624171-113959 + Details
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