Fair Value (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Fair value measurement
Securities available-for-sale	$ 939,944	$ 784,916
US Government Agencies Debt Securities [Member]
Fair value measurement
Securities available-for-sale	107,276	25,364
Mortgage Backed Securities - Residential
Fair value measurement
Securities available-for-sale	216,736	178,743
Mortgage Backed Securities - Commercial
Fair value measurement
Securities available-for-sale	24,424	0
Collateralized Mortgage Obligations
Fair value measurement
Securities available-for-sale	308,038	343,616
State and Municipal Obligations
Fair value measurement
Securities available-for-sale	269,656	233,935
Collateralized Debt Obligations
Fair value measurement
Securities available-for-sale	3,604	3,258
Fair Value, Inputs, Level 1 [Member]
Fair value measurement
Securities available-for-sale	0	0
Fair Value, Inputs, Level 1 [Member] | US Government Agencies Debt Securities [Member]
Fair value measurement
Securities available-for-sale	0	0
Fair Value, Inputs, Level 1 [Member] | Mortgage Backed Securities - Residential
Fair value measurement
Securities available-for-sale	0	0
Fair Value, Inputs, Level 1 [Member] | Mortgage Backed Securities - Commercial
Fair value measurement
Securities available-for-sale	0	0
Fair Value, Inputs, Level 1 [Member] | Collateralized Mortgage Obligations
Fair value measurement
Securities available-for-sale	0	0
Fair Value, Inputs, Level 1 [Member] | State and Municipal Obligations
Fair value measurement
Securities available-for-sale	0	0
Fair Value, Inputs, Level 1 [Member] | Collateralized Debt Obligations
Fair value measurement
Securities available-for-sale	0	0
Fair Value, Inputs, Level 2 [Member]
Fair value measurement
Securities available-for-sale	933,775	778,523
Derivative Assets	1,099	218
Derivative Liability	(1,099)	(218)
Fair Value, Inputs, Level 2 [Member] | US Government Agencies Debt Securities [Member]
Fair value measurement
Securities available-for-sale	107,276	25,364
Fair Value, Inputs, Level 2 [Member] | Mortgage Backed Securities - Residential
Fair value measurement
Securities available-for-sale	216,736	178,743
Fair Value, Inputs, Level 2 [Member] | Mortgage Backed Securities - Commercial
Fair value measurement
Securities available-for-sale	24,424	0
Fair Value, Inputs, Level 2 [Member] | Collateralized Mortgage Obligations
Fair value measurement
Securities available-for-sale	308,038	343,616
Fair Value, Inputs, Level 2 [Member] | State and Municipal Obligations
Fair value measurement
Securities available-for-sale	267,091	230,800
Fair Value, Inputs, Level 2 [Member] | Collateralized Debt Obligations
Fair value measurement
Securities available-for-sale	0	0
Fair Value, Inputs, Level 3 [Member]
Fair value measurement
Securities available-for-sale	6,169	6,393
Fair Value, Inputs, Level 3 [Member] | US Government Agencies Debt Securities [Member]
Fair value measurement
Securities available-for-sale	0	0
Fair Value, Inputs, Level 3 [Member] | Mortgage Backed Securities - Residential
Fair value measurement
Securities available-for-sale	0	0
Fair Value, Inputs, Level 3 [Member] | Mortgage Backed Securities - Commercial
Fair value measurement
Securities available-for-sale	0	0
Fair Value, Inputs, Level 3 [Member] | Collateralized Mortgage Obligations
Fair value measurement
Securities available-for-sale	0	0
Fair Value, Inputs, Level 3 [Member] | State and Municipal Obligations
Fair value measurement
Securities available-for-sale	2,565	3,135
Fair Value, Inputs, Level 3 [Member] | Collateralized Debt Obligations
Fair value measurement
Securities available-for-sale	$ 3,604	$ 3,258