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Variable Interest Entities (Summary of the Impact of Qualifying LIHTC Investments) (Details) - USD ($) $ in Thousands | 12 Months Ended
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Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015
Variable Interest Entity [Line Items] |  |  |
LIHTC credits and benefits, net of amortization | $ (5,327) | $ (6,165) | $ (7,239)
Low income housing tax credits |  |  |
Variable Interest Entity [Line Items] |  |  |
Amortization of qualifying LIHTC investments | 14,037 | 14,223 | 13,496
LIHTC credits and benefits, net of amortization | (11,037) | (10,100) | (9,450)
Other tax benefits related to qualifying LIHTC investments |  |  |
Variable Interest Entity [Line Items] |  |  |
LIHTC credits and benefits, net of amortization | $ (5,045) | $ (9,779) | $ (10,787)

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- Definition Amount of affordable housing tax credits and other tax benefits recognized. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 323 -SubTopic 740 -Section 50 -Paragraph 2 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=64813897&loc=SL49122993-202985 + Details
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- Definition Amount of amortization expense of investment in qualified affordable housing projects. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 323 -SubTopic 740 -Section 50 -Paragraph 2 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=64813897&loc=SL49122993-202985 + Details
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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
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- Details
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