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Junior Subordinated Deferrable Interest Debentures (Key Information) (Details) - USD ($) | 12 Months Ended |  |  |
--- | --- | --- | --- | ---
Dec. 31, 2016 | Nov. 01, 2016 | Dec. 31, 2015 | Jul. 29, 2015
Junior subordinated deferrable interest debentures, major types of business trusts |  |  |  |
Junior subordinated deferrable interest debentures | $ 160,416,000 |  | $ 161,416,000 |
Trust VI |  |  |  |
Junior subordinated deferrable interest debentures, major types of business trusts |  |  |  |
Junior subordinated deferrable interest debentures | $ 25,774,000 |  |  |
Interest rate (as a percent) | 4.36% |  |  |
Interest rate index | 3.45 |  |  |
Trust VIII |  |  |  |
Junior subordinated deferrable interest debentures, major types of business trusts |  |  |  |
Junior subordinated deferrable interest debentures | $ 25,774,000 |  |  |
Interest rate (as a percent) | 3.93% |  |  |
Interest rate index | 3.05 |  |  |
Trust IX |  |  |  |
Junior subordinated deferrable interest debentures, major types of business trusts |  |  |  |
Junior subordinated deferrable interest debentures | $ 41,238,000 |  |  |
Interest rate (as a percent) | 2.47% |  |  |
Interest rate index | 1.62 |  |  |
Trust X |  |  |  |
Junior subordinated deferrable interest debentures, major types of business trusts |  |  |  |
Junior subordinated deferrable interest debentures | $ 21,021,000 |  |  | $ 34,021,000
Interest rate (as a percent) | 2.54% |  |  |
Interest rate index | 1.65 |  |  |
Trust XI |  |  |  |
Junior subordinated deferrable interest debentures, major types of business trusts |  |  |  |
Junior subordinated deferrable interest debentures | $ 25,990,000 | $ 26,990,000 |  | $ 27,990,000
Interest rate (as a percent) | 2.47% |  |  |
Interest rate index | 1.62 |  |  |
Trust XII |  |  |  |
Junior subordinated deferrable interest debentures, major types of business trusts |  |  |  |
Junior subordinated deferrable interest debentures | $ 20,619,000 |  |  |
Interest rate (as a percent) | 2.38% |  |  |
Interest rate index | 1.45 |  |  |
Parent Company |  |  |  |
Junior subordinated deferrable interest debentures, major types of business trusts |  |  |  |
Junior subordinated deferrable interest debentures | $ 160,416,000 |  | $ 161,416,000 |

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- Definition The average effective interest rate during the reporting period. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 835 -SubTopic 30 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28551-108399 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.22(a)(1)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
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- Definition Description of the interest rate as being fixed or variable, and, if variable, identification of the index or rate on which the interest rate is based and the number of points or percentage added to that index or rate to set the rate, and other pertinent information, such as frequency of rate resets. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.22(a)(1)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
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- Definition Including the current and noncurrent portions, the carrying value of junior subordinated long-term debt owed to unconsolidated subsidiary trusts as of the balance sheet date. Such debt places a lender in a lien position behind debt having a higher priority of repayment in liquidation of the entity's assets and was initially scheduled to be repaid after one year or beyond the normal operating cycle if longer. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03.16) -URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03.16) -URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878 + Details
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