Fair Value Measurement - On a Recurring and Nonrecurring Basis (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available-for-sale	$ 434,679	$ 437,754
Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	805	1,067
Total assets at fair value	435,484	438,821
Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	0	0
Total assets at fair value	0	0
Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	805	1,067
Total assets at fair value	435,484	438,821
Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	0	0
Total assets at fair value	0	0
Nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans	3,179	3,086
Loans held for sale	1,511	23,876
Other real estate	664	1,067
Assets held for sale	1,024	1,024
Total assets at fair value	6,378	29,053
Nonrecurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans	0	0
Loans held for sale	0	0
Other real estate	0	0
Assets held for sale	0	0
Total assets at fair value	0	0
Nonrecurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans	0	0
Loans held for sale	1,511	23,876
Other real estate	0	0
Assets held for sale	1,024	1,024
Total assets at fair value	2,535	24,900
Nonrecurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans	3,179	3,086
Loans held for sale	0	0
Other real estate	664	1,067
Assets held for sale	0	0
Total assets at fair value	3,843	4,153
U.S. Government agencies
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available-for-sale	2,977	3,072
U.S. Government agencies | Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available-for-sale	2,977	3,072
U.S. Government agencies | Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available-for-sale	0	0
U.S. Government agencies | Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available-for-sale	2,977	3,072
U.S. Government agencies | Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available-for-sale	0	0
State, county, and municipal securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available-for-sale	28,657	44,088
State, county, and municipal securities | Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available-for-sale	28,657	44,088
State, county, and municipal securities | Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available-for-sale	0	0
State, county, and municipal securities | Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available-for-sale	28,657	44,088
State, county, and municipal securities | Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available-for-sale	0	0
Mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available-for-sale	385,258	365,877
Mortgage-backed securities | Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available-for-sale	385,258	365,877
Mortgage-backed securities | Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available-for-sale	0	0
Mortgage-backed securities | Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available-for-sale	385,258	365,877
Mortgage-backed securities | Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available-for-sale	0	0
Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available-for-sale	17,787	24,717
Corporate debt securities | Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available-for-sale	17,787	24,717
Corporate debt securities | Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available-for-sale	0	0
Corporate debt securities | Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available-for-sale	17,787	24,717
Corporate debt securities | Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available-for-sale	$ 0	$ 0