PARENT COMPANY ONLY CONDENSED FINANCIAL INFORMATION - Condensed Balance Sheets (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Assets:
Cash and cash equivalents	$ 117,194	$ 295,368	$ 94,747	$ 113,838
Other assets	38,399	39,188
Total assets	4,921,520	4,700,744
Liabilities and stockholders' equity:
Subordinated debentures, net	78,920	78,781
Total liabilities	4,424,366	4,246,914
Total stockholders' equity	497,154	453,830	429,200	407,987
Total liabilities and stockholders' equity	4,921,520	4,700,744
Parent Company
Assets:
Cash and cash equivalents	3,663	1,537	$ 7,858	$ 29,049
Other assets	174	103
Investment in the Bank	573,410	532,105
Total assets	577,247	533,745
Liabilities and stockholders' equity:
Subordinated debentures, net	78,920	78,781
Other liabilities	1,173	1,134
Total liabilities	80,093	79,915
Total stockholders' equity	497,154	453,830
Total liabilities and stockholders' equity	$ 577,247	$ 533,745