Loans and Allowance for Credit Losses - Risk Grade and Category of Loan (Parenthetical) (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Financing Receivable Impaired [Line Items]
Loans held for sale	$ 20,315	$ 29,367
Residential Mortgage Loans [Member]
Financing Receivable Impaired [Line Items]
Loans held for sale	$ 20,315	$ 29,367

The face amount of loans that will be sold to other entities.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=82891408&loc=d3e4428-111522

Name:	us-gaap_LoansReceivableHeldForSaleAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant