Derivative Financial Instruments - Effect of Derivatives on Income (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Derivative Instruments, Gain (Loss) [Line Items]
Interest income	$ 37,877	$ 37,694	$ 36,844	$ 34,999	$ 31,849	$ 30,223	$ 27,416	$ 25,979	$ 147,414	$ 115,467	$ 84,697
Interest expense	22,503	22,450	20,739	18,755	16,428	14,253	11,955	10,564	84,447	53,200	30,715
Net interest income	$ 15,374	$ 15,244	$ 16,105	$ 16,244	$ 15,421	$ 15,970	$ 15,461	$ 15,415	62,967	62,267	53,982
Interest rate swaps assets
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Loss Recognized in Other Comprehensive Income in the Twelve Months Ended									(9,071)	(4,358)	0
Interest income									(1,624)	(230)	0
Interest expense									1,091	328	0
Net interest income									(2,715)	(558)	0
Interest rate swaps assets | Loans
Derivative Instruments, Gain (Loss) [Line Items]
Interest income									(1,533)	(100)	0
Interest rate swaps assets | Securities - taxable
Derivative Instruments, Gain (Loss) [Line Items]
Interest income									(127)	(153)	0
Interest rate swaps assets | Securities - non-taxable
Derivative Instruments, Gain (Loss) [Line Items]
Interest income									36	23	0
Interest rate swaps assets | Deposits
Derivative Instruments, Gain (Loss) [Line Items]
Interest expense									618	151	0
Interest rate swaps assets | Other borrowed funds
Derivative Instruments, Gain (Loss) [Line Items]
Interest expense									$ 473	$ 177	$ 0