Parent Company Only Financial Information (Balance Sheets) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Assets:
Cash and interest bearing deposits	$ 273,630	$ 196,003	$ 158,724	$ 258,799
Other assets	114,841	106,141
TOTAL ASSETS	11,408,006	9,810,739
Liabilities and stockholders’ equity:
Other borrowings	274,905	285,011
Accrued expenses and other liabilities	78,078	62,671
TOTAL LIABILITIES	10,082,831	8,819,282
Stockholders’ equity:
Common stock	34,477	29,953
Capital surplus	743,095	503,709
Retained earnings	579,252	481,331
Accumulated other comprehensive loss	(31,649)	(24,474)
TOTAL STOCKHOLDERS' EQUITY	1,325,175	991,457	740,916	663,173
TOTAL LIABILITIES AND EQUITY	11,408,006	9,810,739
Parent
Assets:
Cash and interest bearing deposits	39,666	24,310	$ 65,007	$ 85,327
Investment in subsidiaries	1,538,766	1,194,747
Other assets	30,321	28,536
Due from subsidiaries	6,000	6,000
TOTAL ASSETS	1,614,753	1,253,593
Liabilities and stockholders’ equity:
Other borrowings	269,553	246,438
Accrued expenses and other liabilities	20,025	15,698
TOTAL LIABILITIES	289,578	262,136
Stockholders’ equity:
Preferred stock	0	938
Common stock	34,477	29,953
Capital surplus	743,095	503,709
Retained earnings	579,252	481,331
Accumulated other comprehensive loss	(31,649)	(24,474)
TOTAL STOCKHOLDERS' EQUITY	1,325,175	991,457
TOTAL LIABILITIES AND EQUITY	$ 1,614,753	$ 1,253,593