Loans and Allowance for Credit Losses Summary of Delinquency and Non-Performing Status by Portfolio Segment (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019	Jun. 30, 2019
Financing Receivable, Impaired [Line Items]
Loans	$ 18,704,722	$ 16,837,526	$ 16,368,458
Real-estate - home equity
Financing Receivable, Impaired [Line Items]
Loans	1,251,455	1,314,944	1,386,974
Real estate - residential mortgage
Financing Receivable, Impaired [Line Items]
Loans	2,862,226	2,641,465	2,451,966
Consumer
Financing Receivable, Impaired [Line Items]
Loans	465,610	463,164	452,874
Equipment lease financing, other and overdrafts
Financing Receivable, Impaired [Line Items]
Loans	$ 246,385	$ 299,397	$ 290,876

Amount before allowance and after deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Excludes loans and leases covered under loss sharing agreements.

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=118952595&loc=d3e4428-111522

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=118936363&loc=d3e5074-111524

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