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Impairment of Investment Securities - Pooled Trust Preferred Collateralized Debt Obligations (Detail) $ in Thousands | 12 Months Ended |
--- | --- | ---
Dec. 31, 2015 USD ($) Bank | Dec. 31, 2014 USD ($)
Impairment Of Investment Securities [Line Items] |  |
Amortized Cost | $ 891,111 | $ 1,317,318
Estimated Fair Value of Available for Sale | 886,560 | $ 1,309,819
Mezzanine [Member] |  |
Impairment Of Investment Securities [Line Items] |  |
Amortized Cost | 42,239 |
Estimated Fair Value of Available for Sale | 35,658 |
Unrealized Gain (Loss) | (6,581) |
Mezzanine [Member] | Pre TSL IV [Member] |  |
Impairment Of Investment Securities [Line Items] |  |
Amortized Cost | 1,830 |
Estimated Fair Value of Available for Sale | 1,336 |
Unrealized Gain (Loss) | $ (494) |
Debt Instrument, Credit Rating | B1/BB |
Number of Banks | Bank | 6 |
Deferrals and Defaults as a % of Current Collateral | 18.05% |
Excess Subordination as a % of Current Performing Collateral | 59.91% |
Mezzanine [Member] | Pre TSL VII [Member] |  |
Impairment Of Investment Securities [Line Items] |  |
Amortized Cost | $ 2,963 |
Estimated Fair Value of Available for Sale | 3,484 |
Unrealized Gain (Loss) | $ 521 |
Debt Instrument, Credit Rating | Ca/- |
Number of Banks | Bank | 14 |
Deferrals and Defaults as a % of Current Collateral | 49.68% |
Excess Subordination as a % of Current Performing Collateral | 0.00% |
Mezzanine [Member] | Pre TSL VIII [Member] |  |
Impairment Of Investment Securities [Line Items] |  |
Amortized Cost | $ 2,000 |
Estimated Fair Value of Available for Sale | 1,863 |
Unrealized Gain (Loss) | $ (137) |
Debt Instrument, Credit Rating | C/C |
Number of Banks | Bank | 29 |
Deferrals and Defaults as a % of Current Collateral | 56.74% |
Excess Subordination as a % of Current Performing Collateral | 0.00% |
Mezzanine [Member] | Pre TSL IX [Member] |  |
Impairment Of Investment Securities [Line Items] |  |
Amortized Cost | $ 2,376 |
Estimated Fair Value of Available for Sale | 1,805 |
Unrealized Gain (Loss) | $ (571) |
Debt Instrument, Credit Rating | B1/C |
Number of Banks | Bank | 38 |
Deferrals and Defaults as a % of Current Collateral | 29.80% |
Excess Subordination as a % of Current Performing Collateral | 9.90% |
Mezzanine [Member] | Pre TSL X [Member] |  |
Impairment Of Investment Securities [Line Items] |  |
Amortized Cost | $ 1,613 |
Estimated Fair Value of Available for Sale | 1,915 |
Unrealized Gain (Loss) | $ 302 |
Debt Instrument, Credit Rating | Caa1/C |
Number of Banks | Bank | 43 |
Deferrals and Defaults as a % of Current Collateral | 30.66% |
Excess Subordination as a % of Current Performing Collateral | 0.00% |
Mezzanine [Member] | Pre TSL XII [Member] |  |
Impairment Of Investment Securities [Line Items] |  |
Amortized Cost | $ 5,688 |
Estimated Fair Value of Available for Sale | 4,585 |
Unrealized Gain (Loss) | $ (1,103) |
Debt Instrument, Credit Rating | B3/C |
Number of Banks | Bank | 66 |
Deferrals and Defaults as a % of Current Collateral | 23.07% |
Excess Subordination as a % of Current Performing Collateral | 0.00% |
Mezzanine [Member] | Pre TSL XIII [Member] |  |
Impairment Of Investment Securities [Line Items] |  |
Amortized Cost | $ 12,706 |
Estimated Fair Value of Available for Sale | 10,660 |
Unrealized Gain (Loss) | $ (2,046) |
Debt Instrument, Credit Rating | Ba3/C |
Number of Banks | Bank | 56 |
Deferrals and Defaults as a % of Current Collateral | 11.08% |
Excess Subordination as a % of Current Performing Collateral | 37.45% |
Mezzanine [Member] | Pre TSL XIV [Member] |  |
Impairment Of Investment Securities [Line Items] |  |
Amortized Cost | $ 12,854 |
Estimated Fair Value of Available for Sale | 9,708 |
Unrealized Gain (Loss) | $ (3,146) |
Debt Instrument, Credit Rating | B1/CC |
Number of Banks | Bank | 56 |
Deferrals and Defaults as a % of Current Collateral | 19.72% |
Excess Subordination as a % of Current Performing Collateral | 47.01% |
Mezzanine [Member] | MMCap I [Member] |  |
Impairment Of Investment Securities [Line Items] |  |
Amortized Cost | $ 209 |
Estimated Fair Value of Available for Sale | 302 |
Unrealized Gain (Loss) | $ 93 |
Debt Instrument, Credit Rating | Ca/C |
Number of Banks | Bank | 8 |
Deferrals and Defaults as a % of Current Collateral | 58.11% |
Excess Subordination as a % of Current Performing Collateral | 83.61% |

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