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Allowance for Loan Losses - Recorded Investment in Consumer Loan Classes by Performing and Nonperforming Status (Detail) - USD ($) $ in Thousands | Dec. 31, 2015 | Dec. 31, 2014
--- | --- | ---
Financing Receivable, Recorded Investment [Line Items] |  |
Recorded investment in consumer loan | $ 1,190,735 | $ 976,224
% of Total | 100.00% | 100.00%
Performing Consumer Loan |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Recorded investment in consumer loan | $ 1,182,104 | $ 971,798
% of Total | 99.30% | 99.50%
Non Performing Consumer Loan |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Recorded investment in consumer loan | $ 8,631 | $ 4,426
% of Total | 0.70% | 0.50%
Residential Mortgage |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Recorded investment in consumer loan | $ 639,372 | $ 489,586
% of Total | 100.00% | 100.00%
Residential Mortgage | Performing Consumer Loan |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Recorded investment in consumer loan | $ 633,743 | $ 487,250
% of Total | 99.10% | 99.50%
Residential Mortgage | Non Performing Consumer Loan |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Recorded investment in consumer loan | $ 5,629 | $ 2,336
% of Total | 0.90% | 0.50%
Home Equity |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Recorded investment in consumer loan | $ 470,845 | $ 418,563
% of Total | 100.00% | 100.00%
Home Equity | Performing Consumer Loan |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Recorded investment in consumer loan | $ 467,943 | $ 416,504
% of Total | 99.40% | 99.50%
Home Equity | Non Performing Consumer Loan |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Recorded investment in consumer loan | $ 2,902 | $ 2,059
% of Total | 0.60% | 0.50%
Installment and Other Consumer |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Recorded investment in consumer loan | $ 73,939 | $ 65,567
% of Total | 100.00% | 100.00%
Installment and Other Consumer | Performing Consumer Loan |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Recorded investment in consumer loan | $ 73,839 | $ 65,536
% of Total | 99.80% | 99.90%
Installment and Other Consumer | Non Performing Consumer Loan |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Recorded investment in consumer loan | $ 100 | $ 31
% of Total | 0.20% | 0.10%
Consumer Construction |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Recorded investment in consumer loan | $ 6,579 | $ 2,508
% of Total | 100.00% | 100.00%
Consumer Construction | Performing Consumer Loan |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Recorded investment in consumer loan | $ 6,579 | $ 2,508
% of Total | 100.00% | 100.00%
Consumer Construction | Non Performing Consumer Loan |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Recorded investment in consumer loan | $ 0 | $ 0
% of Total | 0.00% | 0.00%

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- Definition Reflects the aggregate gross carrying amount of all consumer loans and leases held in portfolio, prior to deducting deferred income and the allowance for losses on consumer loans and leases. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=49124121&loc=d3e5074-111524 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=49124121&loc=d3e5066-111524 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=28367877&loc=d3e4428-111522 + Details
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