Fair Value Measurements - Carrying Values and Fair Values of Financial Instruments (Details) - USD ($) $ in Thousands		Mar. 31, 2019	Dec. 31, 2018
ASSETS
Securities, at fair value		$ 680,420	$ 684,872
Portfolio loans, net		5,874,043	5,885,652
FHLB and other restricted stock		19,959	29,435
LIABILITIES
Junior subordinated debt securities		45,619	45,619
Carrying Value
ASSETS
Cash and due from banks, including interest-bearing deposits	[1]	116,820	155,489
Securities, at fair value	[1]	680,420	684,872
Loans held for sale	[1]	2,706	2,371
Portfolio loans, net	[1]	5,874,043	5,885,652
Bank owned life insurance	[1]	74,401	73,900
FHLB and other restricted stock	[1]	19,959	29,435
Securities held in a deferred compensation plan	[1]	5,343	4,725
Mortgage servicing rights	[1]	4,313	4,464
LIABILITIES
Deposits	[1]	5,833,401	5,673,922
Securities sold under repurchase agreements	[1]	23,427	18,383
Short-term borrowings	[1]	235,000	470,000
Long-term borrowings	[1]	70,418	70,314
Junior subordinated debt securities	[1]	45,619	45,619
Carrying Value | Interest rate swaps
ASSETS
Derivative financial assets		10,645	5,504	[1]
LIABILITIES
Interest rate swaps	[1]	10,602	5,340
Carrying Value | Interest rate lock commitments
ASSETS
Derivative financial assets	[1]	339	251
Carrying Value | Forward sale contracts—mortgage loans
ASSETS
Derivative financial assets	[1]	88	55
Fair Value Measurements
ASSETS
Cash and due from banks, including interest-bearing deposits		116,820	155,489
Securities, at fair value		680,420	684,872
Loans held for sale		2,706	2,469
Portfolio loans, net		5,729,524	5,728,843
Bank owned life insurance		74,401	73,900
FHLB and other restricted stock		19,959	29,435
Securities held in a deferred compensation plan		5,343	4,725
Mortgage servicing rights		4,728	5,181
LIABILITIES
Deposits		5,825,873	5,662,193
Securities sold under repurchase agreements		23,427	18,383
Short-term borrowings		235,000	470,000
Long-term borrowings		70,801	70,578
Junior subordinated debt securities		45,619	45,619
Fair Value Measurements | Interest rate swaps
ASSETS
Derivative financial assets		10,645	5,504
LIABILITIES
Interest rate swaps		10,602	5,340
Fair Value Measurements | Interest rate lock commitments
ASSETS
Derivative financial assets		339	251
Fair Value Measurements | Forward sale contracts—mortgage loans
ASSETS
Derivative financial assets		88	55
Fair Value Measurements | Level 1
ASSETS
Cash and due from banks, including interest-bearing deposits		116,820	155,489
Securities, at fair value		0	0
Loans held for sale		0	0
Portfolio loans, net		0	0
Bank owned life insurance		0	0
FHLB and other restricted stock		0	0
Securities held in a deferred compensation plan		5,343	4,725
Mortgage servicing rights		0	0
LIABILITIES
Deposits		4,432,629	4,261,884
Securities sold under repurchase agreements		23,427	18,383
Short-term borrowings		235,000	470,000
Long-term borrowings		39,335	38,610
Junior subordinated debt securities		45,619	45,619
Fair Value Measurements | Level 1 | Interest rate swaps
ASSETS
Derivative financial assets		0	0
LIABILITIES
Interest rate swaps		0	0
Fair Value Measurements | Level 1 | Interest rate lock commitments
ASSETS
Derivative financial assets		0	0
Fair Value Measurements | Level 1 | Forward sale contracts—mortgage loans
ASSETS
Derivative financial assets		0	0
Fair Value Measurements | Level 2
ASSETS
Cash and due from banks, including interest-bearing deposits		0	0
Securities, at fair value		680,420	684,872
Loans held for sale		0	0
Portfolio loans, net		0	0
Bank owned life insurance		74,401	73,900
FHLB and other restricted stock		0	0
Securities held in a deferred compensation plan		0	0
Mortgage servicing rights		0	0
LIABILITIES
Deposits		1,393,244	1,400,309
Securities sold under repurchase agreements		0	0
Short-term borrowings		0	0
Long-term borrowings		31,467	31,968
Junior subordinated debt securities		0	0
Fair Value Measurements | Level 2 | Interest rate swaps
ASSETS
Derivative financial assets		10,645	5,504
LIABILITIES
Interest rate swaps		10,602	5,340
Fair Value Measurements | Level 2 | Interest rate lock commitments
ASSETS
Derivative financial assets		339	251
Fair Value Measurements | Level 2 | Forward sale contracts—mortgage loans
ASSETS
Derivative financial assets		88	55
Fair Value Measurements | Level 3
ASSETS
Cash and due from banks, including interest-bearing deposits		0	0
Securities, at fair value		0	0
Loans held for sale		2,706	2,469
Portfolio loans, net		5,729,524	5,728,843
Bank owned life insurance		0	0
FHLB and other restricted stock		19,959	29,435
Securities held in a deferred compensation plan		0	0
Mortgage servicing rights		4,728	5,181
LIABILITIES
Deposits		0	0
Securities sold under repurchase agreements		0	0
Short-term borrowings		0	0
Long-term borrowings		0	0
Junior subordinated debt securities		0	0
Fair Value Measurements | Level 3 | Interest rate swaps
ASSETS
Derivative financial assets		0	0
LIABILITIES
Interest rate swaps		0	0
Fair Value Measurements | Level 3 | Interest rate lock commitments
ASSETS
Derivative financial assets		0	0
Fair Value Measurements | Level 3 | Forward sale contracts—mortgage loans
ASSETS
Derivative financial assets		$ 0	$ 0

[1] As reported in the Consolidated Balance Sheets