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Summary of Significant Accounting Policies - Premises and Equipment (Details) - USD ($) | 12 Months Ended |  |
--- | --- | --- | ---
Dec. 31, 2017 | Jan. 17, 2017 | Dec. 31, 2016
Transfers and Servicing of Financial Assets |  |  |
Mortgage loans serviced for others | $ 695,100,000 |  | $ 668,200,000
Estimated stranded disproportionate tax expense,net | $ 318,000 |  |
Subsequent Events |  |  |
Cash dividend declared (per share) |  | $ 0.01 |
Buildings | Minimum |  |  |
Premises and equipment |  |  |
Useful lives | 25 years |  |
Buildings | Maximum |  |  |
Premises and equipment |  |  |
Useful lives | 40 years |  |
Building improvements | Minimum |  |  |
Premises and equipment |  |  |
Useful lives | 3 years |  |
Building improvements | Maximum |  |  |
Premises and equipment |  |  |
Useful lives | 15 years |  |
Furniture and equipment | Minimum |  |  |
Premises and equipment |  |  |
Useful lives | 3 years |  |
Furniture and equipment | Maximum |  |  |
Premises and equipment |  |  |
Useful lives | 10 years |  |

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- Definition Fair value as of the balance sheet date of mortgage loans representing net future revenues from contractually specified servicing fees, late charges, and other ancillary revenues, in excess of future costs related to servicing arrangements. + References No definition available. + Details
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- Definition Amount of the related income tax effect of a cumulative effect on retained earnings. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 250 -SubTopic 10 -Section 50 -Paragraph 9 -URI http://asc.fasb.org/extlink&oid=64853466&loc=d3e22663-107794 + Details
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- Definition Useful life of long lived, physical assets used in the normal conduct of business and not intended for resale, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Examples include, but not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment. + References No definition available. + Details
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