Revenue from Contracts with Customers Revenue from Contracts with Customers (Schedule of Deposit Account Charges and Other Fees) (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Deposit Account Charges and Other Fees [Line Items]
Deposit account charges and other fees	$ 23,893	$ 22,861	$ 46,875	$ 44,803
Corporate Cash Management [Member]
Deposit Account Charges and Other Fees [Line Items]
Deposit account charges and other fees	10,095	9,477	19,492	18,388
Overdraft and Return Item [Member]
Deposit Account Charges and Other Fees [Line Items]
Deposit account charges and other fees	7,656	7,448	15,168	14,628
Other Deposit Account Charges [Member]
Deposit Account Charges and Other Fees [Line Items]
Deposit account charges and other fees	$ 6,142	$ 5,936	$ 12,215	$ 11,787

Includes amounts charged depositors for: (1) maintenance of their accounts (maintenance charges); (2) failure to maintain specified minimum balances on account; (3) exceeding the number of checks or transactions allowed to be processed in a given period; (4) checks drawn on no minimum balance deposit accounts; (5) withdrawals from nontransaction deposit accounts; (6) closing savings accounts before a specified minimum period of time has elapsed; (7) accounts which have remained inactive for extended periods of time or which have become dormant; (8) use of automated teller machines or remote service units; (9) checks drawn against insufficient funds that the bank assesses regardless of whether it decides to pay, return or hold the check; (10) issuing stop payment orders; (11) certifying checks; and (12) accumulating or disbursing funds deposited in IRAs or Keogh Plan accounts when not handled by the bank's trust department. This item does not include penalties assessed on the early withdrawal of time deposits.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 225
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04.13 (d))
-URI http://asc.fasb.org/extlink&oid=6879574&loc=d3e536633-122882

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration