Fair Value Measurement - Schedule of Assets Measured on Recurring and Non-recurring Basis (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	$ 528,064	$ 689,202
Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	528,064	689,202
Derivatives	5,886	1,898
Total financial assets	542,290	695,710
Fair Value, Measurements, Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	100	203,597
Derivatives	0	0
Total financial assets	8,440	208,207
Fair Value, Measurements, Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	527,964	485,605
Derivatives	5,886	1,898
Total financial assets	533,850	487,503
Fair Value, Measurements, Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	0	0
Derivatives	0	0
Total financial assets	0	0
Fair Value, Measurements, Recurring | U.S. Treasury securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	100	200,088
Fair Value, Measurements, Recurring | U.S. Treasury securities | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	100	200,088
Fair Value, Measurements, Recurring | U.S. Treasury securities | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	0	0
Fair Value, Measurements, Recurring | U.S. Treasury securities | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	0	0
Fair Value, Measurements, Recurring | Obligations of the U.S. government and agencies
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	190,453	151,044
Fair Value, Measurements, Recurring | Obligations of the U.S. government and agencies | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	0	0
Fair Value, Measurements, Recurring | Obligations of the U.S. government and agencies | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	190,453	151,044
Fair Value, Measurements, Recurring | Obligations of the U.S. government and agencies | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	0	0
Fair Value, Measurements, Recurring | Obligations of state and political subdivisions
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	15,799	21,310
Fair Value, Measurements, Recurring | Obligations of state and political subdivisions | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	0	0
Fair Value, Measurements, Recurring | Obligations of state and political subdivisions | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	15,799	21,310
Fair Value, Measurements, Recurring | Obligations of state and political subdivisions | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	0	0
Fair Value, Measurements, Recurring | Mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	284,421	274,990
Fair Value, Measurements, Recurring | Mortgage-backed securities | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	0	0
Fair Value, Measurements, Recurring | Mortgage-backed securities | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	284,421	274,990
Fair Value, Measurements, Recurring | Mortgage-backed securities | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	0	0
Fair Value, Measurements, Recurring | Collateralized mortgage obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	36,193	36,662
Fair Value, Measurements, Recurring | Collateralized mortgage obligations | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	0	0
Fair Value, Measurements, Recurring | Collateralized mortgage obligations | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	36,193	36,662
Fair Value, Measurements, Recurring | Collateralized mortgage obligations | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	0	0
Fair Value, Measurements, Recurring | Other investment securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	1,098	1,599
Fair Value, Measurements, Recurring | Other investment securities | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	0	0
Fair Value, Measurements, Recurring | Other investment securities | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	1,098	1,599
Fair Value, Measurements, Recurring | Other investment securities | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	0	0
Fair Value, Measurements, Recurring | Mutual funds with no stated maturity
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value		3,509
Investment securities trading	8,340	4,610
Fair Value, Measurements, Recurring | Mutual funds with no stated maturity | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value		3,509
Investment securities trading	8,340	4,610
Fair Value, Measurements, Recurring | Mutual funds with no stated maturity | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value		0
Investment securities trading	0	0
Fair Value, Measurements, Recurring | Mutual funds with no stated maturity | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value		0
Investment securities trading	0	0
Fair Value, Measurements, Nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total financial assets	19,708	20,655
MSRs	6,586	6,397
Impaired loans and leases	12,593	13,954
OREO	529	304
Fair Value, Measurements, Nonrecurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total financial assets	0	0
MSRs	0	0
Impaired loans and leases	0	0
OREO	0	0
Fair Value, Measurements, Nonrecurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total financial assets	0	0
MSRs	0	0
Impaired loans and leases	0	0
OREO	0	0
Fair Value, Measurements, Nonrecurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total financial assets	19,708	20,655
MSRs	6,586	6,397
Impaired loans and leases	12,593	13,954
OREO	$ 529	$ 304