Parent Company Financial Information - Balance Sheet (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Assets
Investment securities available-for-sale, at fair value (amortized cost of $1,129,057 and $838,994 and allowance for credit losses of $167 and $0 as of December 31, 2020 and December 31, 2019, respectively).	$ 1,150,885	$ 843,165
Other assets	134,531	85,644
Total Assets	11,117,802	8,988,719
Liabilities
Other liabilities	59,384	45,021
Long-term borrowings	268,077	217,687
Total Liabilities	9,876,910	7,798,038
Shareholders’ Equity
Common stock	315	331
Additional paid in capital	427,016	482,286
Retained earnings	798,061	705,105
Accumulated other comprehensive income	15,500	2,959
Total Shareholders’ Equity	1,240,892	1,190,681	$ 1,108,941	$ 950,438
Total Liabilities and Shareholders’ Equity	11,117,802	8,988,719
Parent Company
Assets
Cash	29,275	43,204
Investment securities available-for-sale, at fair value (amortized cost of $1,129,057 and $838,994 and allowance for credit losses of $167 and $0 as of December 31, 2020 and December 31, 2019, respectively).	16,716	7,218
Investment in subsidiaries	1,347,235	1,334,197
Other assets	79,590	30,773
Total Assets	1,472,816	1,415,392
Liabilities
Other liabilities	13,847	7,024
Long-term borrowings	218,077	217,687
Total Liabilities	231,924	224,711
Shareholders’ Equity
Common stock	315	331
Additional paid in capital	427,016	482,286
Retained earnings	798,061	705,105
Accumulated other comprehensive income	15,500	2,959
Total Shareholders’ Equity	1,240,892	1,190,681
Total Liabilities and Shareholders’ Equity	$ 1,472,816	$ 1,415,392