Affordable Housing Projects Tax Credit Partnership - Tax credits and other tax benefits (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Proportional Amortization Method
Tax credits and other tax benefits recognized	$ 340	$ 276	$ 995	$ 785
Amortization expense in federal income taxes	$ 292	$ 234	$ 861	$ 703

Amount of deferred income tax expense (benefit) and income tax credits.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-URI http://asc.fasb.org/extlink&oid=118932676&loc=d3e3602-108585

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration