Variable Interest Entities Amortization Expense and Tax Credits and Other Tax Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Investments in Qualified Affordable Housing Projects
Amortization expense	$ 4,926	$ 2,507	$ 1,125
Tax credits and other tax benefits recognized	$ 6,550	$ 3,827	$ 1,515

Amount of amortization expense of investment in qualified affordable housing projects.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 323
-SubTopic 740
-Section 50
-Paragraph 2
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=114775393&loc=SL49122993-202985

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