Investment Securities - Additional Information (Detail)
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12 Months Ended |
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Dec. 31, 2015
USD ($)
Investmentsecurities
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Dec. 31, 2014
USD ($)
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Dec. 31, 2013
USD ($)
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| Investment Securities [Line Items] |
|
|
|
| Investment securities sold |
$ 2,000
|
$ 14,130,000
|
$ 0
|
| Gain or loss on sale of investment securities |
0
|
|
|
| Investment securities carrying value |
297,547,000
|
$ 143,992,000
|
|
| Mortgage-backed securities |
$ 1,024,911,000
|
|
|
| Life of mortgage-backed securities |
5 years 10 months 24 days
|
|
|
| Obligations of U.S. Government Corporations and Agencies [Member] |
|
|
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| Investment Securities [Line Items] |
|
|
|
| Debt securities | Investmentsecurities |
29
|
|
|
| Percentage of aggregate depreciation in unrealized losses |
1.23%
|
|
|
| Obligations of States and Political Subdivisions [Member] |
|
|
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| Investment Securities [Line Items] |
|
|
|
| Debt securities | Investmentsecurities |
10
|
|
|
| Percentage of aggregate depreciation in unrealized losses |
1.73%
|
|
|
| Marketable Equity Securities [Member] |
|
|
|
| Investment Securities [Line Items] |
|
|
|
| Percentage of aggregate depreciation in unrealized losses |
0.05%
|
|
|