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Allowance for Loan Losses - Recorded Investment in Commercial Loan Classes by Internally Assigned Risk Ratings (Detail) - Commercial - USD ($) $ in Thousands | Sep. 30, 2016 | Dec. 31, 2015
--- | --- | ---
Financing Receivable, Recorded Investment [Line Items] |  |
Loans and leases receivables, recorded investment | $ 4,173,585 | $ 3,836,877
Total percentage of recorded investment in commercial loan | 100.00% | 100.00%
Pass |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Loans and leases receivables, recorded investment | $ 3,975,265 | $ 3,653,344
Total percentage of recorded investment in commercial loan | 95.20% | 95.20%
Special Mention |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Loans and leases receivables, recorded investment | $ 81,464 | $ 83,680
Total percentage of recorded investment in commercial loan | 2.00% | 2.20%
Substandard |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Loans and leases receivables, recorded investment | $ 116,856 | $ 99,853
Total percentage of recorded investment in commercial loan | 2.80% | 2.60%
Commercial and Industrial |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Loans and leases receivables, recorded investment | $ 1,344,297 | $ 1,256,830
Total percentage of recorded investment in commercial loan | 100.00% | 100.00%
Commercial and Industrial | Pass |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Loans and leases receivables, recorded investment | $ 1,253,411 | $ 1,182,685
Total percentage of recorded investment in commercial loan | 93.20% | 94.10%
Commercial and Industrial | Special Mention |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Loans and leases receivables, recorded investment | $ 37,079 | $ 43,896
Total percentage of recorded investment in commercial loan | 2.80% | 3.50%
Commercial and Industrial | Substandard |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Loans and leases receivables, recorded investment | $ 53,807 | $ 30,249
Total percentage of recorded investment in commercial loan | 4.00% | 2.40%
Commercial Real Estate |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Loans and leases receivables, recorded investment | $ 2,427,164 | $ 2,166,603
Total percentage of recorded investment in commercial loan | 100.00% | 100.00%
Commercial Real Estate | Pass |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Loans and leases receivables, recorded investment | $ 2,346,848 | $ 2,094,851
Total percentage of recorded investment in commercial loan | 96.70% | 96.70%
Commercial Real Estate | Special Mention |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Loans and leases receivables, recorded investment | $ 30,050 | $ 19,938
Total percentage of recorded investment in commercial loan | 1.20% | 0.90%
Commercial Real Estate | Substandard |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Loans and leases receivables, recorded investment | $ 50,266 | $ 51,814
Total percentage of recorded investment in commercial loan | 2.10% | 2.40%
Commercial Construction |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Loans and leases receivables, recorded investment | $ 402,124 | $ 413,444
Total percentage of recorded investment in commercial loan | 99.99% | 100.00%
Commercial Construction | Pass |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Loans and leases receivables, recorded investment | $ 375,006 | $ 375,808
Total percentage of recorded investment in commercial loan | 93.20% | 90.90%
Commercial Construction | Special Mention |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Loans and leases receivables, recorded investment | $ 14,335 | $ 19,846
Total percentage of recorded investment in commercial loan | 3.60% | 4.80%
Commercial Construction | Substandard |  |
Financing Receivable, Recorded Investment [Line Items] |  |
Loans and leases receivables, recorded investment | $ 12,783 | $ 17,790
Total percentage of recorded investment in commercial loan | 3.20% | 4.30%

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- Definition Amount before allowance of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Includes deferred interest and fees, undisbursed portion of loan balance, unamortized costs and premiums and discounts from face amounts. Excludes loans and leases covered under loss sharing agreements. + References Reference 1: 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=65884687&loc=d3e4428-111522 + Details
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