Loans and Leases Held for Investment and Credit Quality - Activity in the Allowance for Loan and Lease Losses by Portfolio Segment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Allowance for Loan Losses:
Beginning Balance	$ 32,434	$ 24,190	$ 18,209
Charge offs	(4,290)	(5,497)	(3,852)
Recoveries	530	683	297
Provision	19,573	13,058	9,536
Ending Balance	48,247	32,434	24,190
Construction & Development
Allowance for Loan Losses:
Beginning Balance	2,042	2,030	1,693
Provision	689	12	337
Ending Balance	2,731	2,042	2,030
Commercial Real Estate
Allowance for Loan Losses:
Beginning Balance	11,044	9,180	5,897
Charge offs	(1,179)	(1,041)	(1,177)
Recoveries	33	190	191
Provision	4,684	2,715	4,269
Ending Balance	14,582	11,044	9,180
Commercial & Industrial
Allowance for Loan Losses:
Beginning Balance	14,562	10,751	8,413
Charge offs	(2,784)	(4,215)	(2,617)
Recoveries	492	493	101
Provision	13,143	7,533	4,854
Ending Balance	25,413	14,562	10,751
Commercial Land
Allowance for Loan Losses:
Beginning Balance	4,786	2,229	2,206
Charge offs	(327)	(241)	(58)
Recoveries	5		5
Provision	1,057	2,798	76
Ending Balance	$ 5,521	$ 4,786	$ 2,229