Business Segment Information (Disaggregation of Revenue) (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Disaggregation of Revenue [Line Items]
Fixed income	$ 37,697	$ 55,110	$ 83,203	$ 105,788
Deposit transactions and cash management	36,083	27,858	72,067	52,423
Brokerage, management fees and commissions	13,740	12,029	27,223	23,935
Trust services and investment management	8,132	7,698	15,409	14,351
Bankcard income	6,635	5,605	13,080	11,060
Bank-owned life insurance	5,773	4,351	9,766	7,598
Debt securities gains/(losses), net	0	405	52	449
Equity securities gains/(losses), net	31	0	65	0
All other income and commissions	19,434	14,617	42,677	29,008
Total noninterest income	127,525	127,673	263,542	244,612
Gain on sale of a building			3,300
Underwriting, Portfolio Advisory, and Other Noninterest Income
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	7,300		15,600
Regional Banking
Disaggregation of Revenue [Line Items]
Fixed income	130	139	211	213
Deposit transactions and cash management	34,522	26,433	69,262	49,667
Brokerage, management fees and commissions	13,740	12,029	27,223	23,935
Trust services and investment management	8,146	7,712	15,438	14,392
Bankcard income	6,658	5,495	12,951	10,837
Bank-owned life insurance	0	0	0	0
Debt securities gains/(losses), net	0	386	0	386
Equity securities gains/(losses), net	0	0	0	0
All other income and commissions	15,372	12,546	32,336	24,288
Total noninterest income	78,568	64,740	157,421	123,718
Fixed Income
Disaggregation of Revenue [Line Items]
Fixed income	37,567	54,971	82,992	105,575
Deposit transactions and cash management	3	0	6	0
Brokerage, management fees and commissions	0	0	0	0
Trust services and investment management	0	0	0	0
Bankcard income	0	0	0	0
Bank-owned life insurance	0	0	0	0
Debt securities gains/(losses), net	0	0	0	0
Equity securities gains/(losses), net	0	0	0	0
All other income and commissions	793	236	970	455
Total noninterest income	38,363	55,207	83,968	106,030
Corporate
Disaggregation of Revenue [Line Items]
Fixed income	0	0	0	0
Deposit transactions and cash management	1,497	1,376	2,691	2,665
Brokerage, management fees and commissions	0	0	0	0
Trust services and investment management	(14)	(14)	(29)	(41)
Bankcard income	55	57	112	113
Bank-owned life insurance	5,773	4,351	9,766	7,598
Debt securities gains/(losses), net	0	19	52	63
Equity securities gains/(losses), net	31	0	65	0
All other income and commissions	1,506	430	5,670	1,297
Total noninterest income	8,848	6,219	18,327	11,695
Non-Strategic
Disaggregation of Revenue [Line Items]
Fixed income	0	0	0	0
Deposit transactions and cash management	61	49	108	91
Brokerage, management fees and commissions	0	0	0	0
Trust services and investment management	0	0	0	0
Bankcard income	(78)	53	17	110
Bank-owned life insurance	0	0	0	0
Debt securities gains/(losses), net	0	0	0	0
Equity securities gains/(losses), net	0	0	0	0
All other income and commissions	1,763	1,405	3,701	2,968
Total noninterest income	$ 1,746	$ 1,507	$ 3,826	$ 3,169

Bankcard Other Income

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Acting as an agent, a broker-dealer may buy and sell securities on behalf of its customers. In return for such services, the broker-dealer charges a commission. Each time a customer enters into a buy or sell transaction, a commission is earned by the broker-dealer for its selling and administrative efforts. For securities purchased, the commission is recorded as a receivable from customers; for securities sold, it is recorded as reductions in the payable to customers. Commissions earned are usually related to the broker-dealer's customers' trading volume and the dollar amounts of the trades. In general, commissions are for smaller trades of exchange-listed stocks and bonds made by retail customers. Revenue recognized in the period for (1) performance (incentive) fees based on the investment results achieved for management of certain institutional accounts and hedge funds, (2) schedule-based fees earned for management of mutual funds and closed-end funds, based either on average daily net assets or on a combination of the average daily net assets and gross income, and (3) other investment management and advisory fees.

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Debt Securities, Realized Gain (Loss)

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Deposit transactions and cash management.

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Equity Securities, FV-NI, Realized Gain (Loss)

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The major component of revenue in this line item is generated from the purchase and sale of securities as both principal and agent, and from other fee sources including loan sales, portfolio advisory, and derivative sales.

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No definition available.

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Earnings on or other increases in the value of the cash surrender value of bank owned life insurance policies.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Income from services rendered by trust departments or by any consolidated subsidiaries acting in a fiduciary capacity, including fees earned for (1) acting as an agent for fiduciary placement and loans and (2) custody or investment advisory services when such fees are not separately billed to the customer. This item excludes commissions and fees received for the accumulation or disbursement of funds deposited to Individual Retirement or Keogh plan accounts when such are not handled by the reporting entity's trust department.

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The difference between the carrying value and the sale price of real estate or properties that were intended to be sold or held for capital appreciation or rental income. This element refers to the gain (loss) included in earnings and not to the cash proceeds of the sale. This element is a noncash adjustment to net income when calculating net cash generated by operating activities using the indirect method.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
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The total amount of noninterest income which may be derived from: (1) fees and commissions; (2) premiums earned; (3) insurance policy charges; (4) the sale or disposal of assets; and (5) other sources not otherwise specified.

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Amount of revenue earned, classified as other, excluding interest income.

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Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

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