CONSOLIDATED STATEMENTS OF INCOME AND OTHER COMPREHENSIVE INCOME - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Interest income
Interest and fees on loans	$ 1,284,036	$ 1,124,970	$ 846,292
Investment securities	8,654	2,834	1,066
Federal funds sold and securities purchased under resale agreements	1,529	3,792	2,542
Interest-bearing deposits in other banks	71,093	32,597	29,399
Total interest income	1,365,312	1,164,193	879,299
Interest expense
Deposits	293,537	185,116	79,886
Federal funds purchased	11,872	6,531	2,592
Other borrowings	58,393	36,207	15,137
Subordinated notes	16,764	16,764	16,764
Trust preferred subordinated debentures	5,026	4,715	3,592
Total interest expense	385,592	249,333	117,971
Net interest income	979,720	914,860	761,328
Provision for credit losses	75,000	87,000	44,000
Net interest income after provision for credit losses	904,720	827,860	717,328
Non-interest income
Service charges on deposit accounts	11,320	12,787	12,432
Wealth management and trust fee income	8,810	8,148	6,153
Brokered loan fees	29,738	22,532	23,331
Servicing income	13,439	18,307	15,657
Swap fees	4,387	5,625	3,990
Net gain/(loss) on sale of loans held for sale	(20,259)	(15,934)	(2,387)
Other	45,005	26,559	15,080
Total non-interest income	92,440	78,024	74,256
Non-interest expense
Salaries and employee benefits	315,080	291,768	264,231
Net occupancy expense	32,989	30,342	25,811
Marketing	53,355	39,335	26,787
Legal and professional	53,830	42,990	29,731
Communications and technology	44,826	30,056	31,004
FDIC insurance assessment	20,093	24,307	23,510
Servicing related expenses	22,573	14,934	15,506
Allowance and other carrying costs for other real estate owned	7	474	6,437
Other	47,246	50,890	42,859
Total non-interest expense	589,999	525,096	465,876
Income before income taxes	407,161	380,788	325,708
Income tax expense	84,295	79,964	128,645
Net income	322,866	300,824	197,063
Preferred stock dividends	(9,750)	(9,750)	(9,750)
Net income available to common stockholders	313,116	291,074	187,313
Other comprehensive income (loss)
Change in unrealized gain (loss) on available-for-sale debt securities arising during period, before tax	10,674	7	19
Income tax expense (benefit) related to unrealized loss on available-for-sale debt securities	2,242	1	6
Other comprehensive income (loss), net of tax	8,432	6	13
Comprehensive income	$ 331,298	$ 300,830	$ 197,076
Basic earnings per common share
Basic earnings per common share	$ 6.23	$ 5.83	$ 3.78
Diluted earnings per common share
Diluted earnings per common share	$ 6.21	$ 5.79	$ 3.73