Business Segment Information - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2019	Mar. 31, 2018
Disaggregation of Revenue [Line Items]
Fixed income	$ 53,749	$ 45,506
Deposit transactions and cash management	31,621	35,984
Brokerage, management fees and commissions	12,633	13,483
Trust services and investment management	7,026	7,277
Bankcard income	6,015	6,445
Bank-owned life insurance (BOLI)	4,402	3,993
Debt securities gains/(losses), net	0	52
Equity securities gains/(losses), net	31	34
All other income and commissions (Note 8)	25,568	23,243
Total noninterest income	141,045	136,017
Gain on sale of a building		3,300
Regional Banking
Disaggregation of Revenue [Line Items]
Fixed income	17	81
Deposit transactions and cash management	30,005	34,722
Brokerage, management fees and commissions	12,629	13,483
Trust services and investment management	7,056	7,292
Bankcard income	6,102	6,279
Bank-owned life insurance (BOLI)	0	0
Debt securities gains/(losses), net	0	0
Equity securities gains/(losses), net	0	0
All other income and commissions (Note 8)	16,308	18,106
Total noninterest income	72,117	79,963
Fixed Income
Disaggregation of Revenue [Line Items]
Fixed income	53,732	45,425
Deposit transactions and cash management	3	3
Brokerage, management fees and commissions	0	0
Trust services and investment management	0	0
Bankcard income	0	0
Bank-owned life insurance (BOLI)	0	0
Debt securities gains/(losses), net	0	0
Equity securities gains/(losses), net	0	0
All other income and commissions (Note 8)	72	177
Total noninterest income	53,807	45,605
Corporate
Disaggregation of Revenue [Line Items]
Fixed income	0	0
Deposit transactions and cash management	1,563	1,209
Brokerage, management fees and commissions	0	0
Trust services and investment management	(30)	(15)
Bankcard income	62	56
Bank-owned life insurance (BOLI)	4,402	3,993
Debt securities gains/(losses), net	0	52
Equity securities gains/(losses), net	31	34
All other income and commissions (Note 8)	7,324	3,987
Total noninterest income	13,352	9,316
Non-Strategic
Disaggregation of Revenue [Line Items]
Fixed income	0	0
Deposit transactions and cash management	50	50
Brokerage, management fees and commissions	4	0
Trust services and investment management	0	0
Bankcard income	(149)	110
Bank-owned life insurance (BOLI)	0	0
Debt securities gains/(losses), net	0	0
Equity securities gains/(losses), net	0	0
All other income and commissions (Note 8)	1,864	973
Total noninterest income	1,769	1,133
Underwriting, Portfolio Advisory, and Other Noninterest Income
Disaggregation of Revenue [Line Items]
Fixed income	$ 7,300	$ 8,200

Bankcard Other Income

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- Definition

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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Deposit transactions and cash management.

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- Definition

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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Trust Services And Investment Management

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No definition available.

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- Definition

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

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 220
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04.13)
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Amount of realized gain (loss) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), investment in debt security measured at amortized cost (held-to-maturity) and investment in debt security measured at fair value with change in fair value recognized in net income (trading).

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No definition available.

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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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No definition available.

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Amount of realized gain (loss) from sale of investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI).

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 321
-SubTopic 10
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=84241550&loc=SL75117546-209714

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- Definition

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.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 360
-SubTopic 10
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- Definition

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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- Definition

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

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
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