Securities - Amortized Cost and Fair Value of Securities (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Available-for-sale debt securities
Total	$ 703,095	$ 717,682
Gross Unrealized Gains	30,558	22,377
Gross Unrealized Losses	629	586
Approximate Fair Value	733,024	739,473
Equity securities
Amortized Cost	2,202	2,190
Gross Unrealized Gains	5	0
Gross Unrealized Losses	0	29
Approximate Fair Value	2,207	2,161
Total available-for-sale securities
Amortized Cost	705,297	719,872
Gross Unrealized Gains	30,563	22,377
Gross Unrealized Losses	629	615
Approximate Fair Value	735,231	741,634
Mortgage-backed - GSE residential
Available-for-sale debt securities
Total	144,175	151,037
Gross Unrealized Gains	5,646	1,668
Gross Unrealized Losses	0	193
Approximate Fair Value	149,821	152,512
Collateralized mortgage obligations - GSE residential
Available-for-sale debt securities
Total	115,734	128,876
Gross Unrealized Gains	3,206	625
Gross Unrealized Losses	2	289
Approximate Fair Value	118,938	129,212
State and political subdivisions
Available-for-sale debt securities
Total	441,888	436,448
Gross Unrealized Gains	21,589	19,996
Gross Unrealized Losses	627	104
Approximate Fair Value	462,850	456,340
Corporate bonds
Available-for-sale debt securities
Total	1,298	1,321
Gross Unrealized Gains	117	88
Gross Unrealized Losses	0	0
Approximate Fair Value	1,415	1,409
Mutual funds
Equity securities
Amortized Cost	2,202	2,190
Gross Unrealized Gains	5	0
Gross Unrealized Losses	0	29
Approximate Fair Value	$ 2,207	$ 2,161

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