Parent Company Only Financial Statements Condensed balance sheets (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Condensed Financial Statements, Captions [Line Items]
Premises and equipment, net	$ 59,117	$ 38,266
Other assets	27,612	18,976
Total assets	3,839,734	2,841,539
Other liabilities	24,627	8,595
Total liabilities	3,363,870	2,533,575
Stockholders’ equity	475,864	307,964	$ 280,673	$ 205,009
Total liabilities and stockholders’ equity	3,839,734	2,841,539
Parent Company [Member]
Condensed Financial Statements, Captions [Line Items]
Cash	18,571	8,296
Premises and equipment, net	3,127	2,654
Investment in subsidiaries	498,544	328,830
Other assets	4,637	3,555
Total assets	524,879	343,335
Debt	29,000	34,313
Other liabilities	20,015	1,058
Total liabilities	49,015	35,371
Stockholders’ equity	475,864	307,964
Total liabilities and stockholders’ equity	$ 524,879	$ 343,335