Fair Value Measurements (Carrying Amounts and Estimated Fair Values of Financial Instruments) (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Held to maturity securities	$ 10,863	$ 12,541
Loans, net of allowance of loan losses	3,529,694	3,347,583
Federal Home Loan Bank advances	828,392	791,356
Junior subordinated debentures	22,681	22,681
Reported Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Held to maturity securities	10,863	12,541
Loans, net of allowance of loan losses	3,529,694	3,347,583
Time deposits	1,159,218	1,015,095
Federal Home Loan Bank advances	828,392	791,356
Junior subordinated debentures	22,681	22,681
Fair Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Held to maturity securities	10,657	12,721
Loans, net of allowance of loan losses	3,500,065	3,369,932
Time deposits	1,170,151	1,018,396
Federal Home Loan Bank advances	827,328	792,887
Junior subordinated debentures	19,844	18,559
Fair Value Measurement [Member] \| Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Held to maturity securities	0	0
Loans, net of allowance of loan losses	0	0
Time deposits	0	0
Federal Home Loan Bank advances	0	0
Junior subordinated debentures	0	0
Fair Value Measurement [Member] \| Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Held to maturity securities	10,657	12,721
Loans, net of allowance of loan losses	0	0
Time deposits	1,170,151	1,018,396
Federal Home Loan Bank advances	827,328	792,887
Junior subordinated debentures	19,844	18,559
Fair Value Measurement [Member] \| Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Held to maturity securities	0	0
Loans, net of allowance of loan losses	3,500,065	3,369,932
Time deposits	0	0
Federal Home Loan Bank advances	0	0
Junior subordinated debentures	$ 0	$ 0

Amount of borrowings as of the balance sheet date from the Federal Home Loan Bank, which are primarily used to cover shortages in the required reserve balance and liquidity shortages.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 470
-Section 45
-Paragraph 1
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Amount after other than temporary impairment (OTTI) accretion, of investments in debt securities classified as held-to-maturity.

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Including the current and noncurrent portions, the carrying value of junior subordinated long-term debt owed to unconsolidated subsidiary trusts as of the balance sheet date. Such debt places a lender in a lien position behind debt having a higher priority of repayment in liquidation of the entity's assets and was initially scheduled to be repaid after one year or beyond the normal operating cycle if longer.

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Amount after allowance and 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 and loans held for sale.

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Amount of time deposit liabilities, including certificates of deposit.

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