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Variable Interest Entities (Summary of the Impact of Qualifying LIHTC Investments) (Details) - USD ($) $ in Thousands | 3 Months Ended | 9 Months Ended
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Sep. 30, 2017 | Sep. 30, 2016 | Sep. 30, 2017 | Sep. 30, 2016
Low income housing tax credits |  |  |  |
Variable Interest Entity [Line Items] |  |  |  |
Amortization of qualifying LIHTC investments | $ 3,774 | $ 5,445 | $ 8,414 | $ 10,073
Affordable Housing Tax Credits and Other Tax Benefits | (3,103) | (2,615) | (8,101) | (7,672)
Other tax benefits related to qualifying LIHTC investments |  |  |  |
Variable Interest Entity [Line Items] |  |  |  |
Affordable Housing Tax Credits and Other Tax Benefits | $ (2,478) | $ (6,131) | $ (4,307) | $ (8,310)

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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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