Investments in Qualified Affordable Housing Projects - Components of Qualified Affordable Housing Projects Included in Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Equity Method Investments and Joint Ventures [Abstract]
Tax credit amortization	$ 410	$ 262	$ 804	$ 523
Tax credits and other benefits	(572)	(388)	(1,145)	(848)
Total	$ (162)	$ (126)	$ (341)	$ (325)

Affordable Housing Tax Credits and Other Benefits, Net of Amortization

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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

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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

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- References

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