Segment Reporting Segment Reporting Narrative (Details) $ in Thousands	12 Months Ended
Dec. 31, 2017 USD ($) Segment	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Segment Reporting Information [Line Items]
Number of Reportable Segments \| Segment	3
Loans and leases	$ 17,523,858	$ 17,026,588	$ 15,671,735
Consumer Portfolio Segment [Member]
Segment Reporting Information [Line Items]
Loans and leases	$ 2,590,225	2,684,500	$ 2,702,560
Consumer Portfolio Segment [Member] \| Home Equity Liquidating Portfolio [Member]
Segment Reporting Information [Line Items]
Loans and leases		$ 65,000

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://www.xbrl.org/2003/role/presentationRef
-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

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=84173941&loc=d3e5074-111524

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