Consolidated Statements of Income and Comprehensive Income (unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Interest income
Interest and fees on loans	$ 166,358	$ 172,351	$ 505,276	$ 518,938
Interest on taxable securities	5,296	7,259	16,658	26,688
Interest on nontaxable securities	139	159	419	473
Interest on deposits in other banks and federal funds sold	1,253	165	2,394	1,621
Total interest income	173,046	179,934	524,747	547,720
Interest expense
Interest on deposits	5,106	11,822	17,679	50,197
Interest on other borrowings	6,279	5,574	18,578	23,226
Total interest expense	11,385	17,396	36,257	73,423
Net interest income	161,661	162,538	488,490	474,297
Provision for loan losses	(3,984)	26,692	(21,462)	132,188
Provision for unfunded commitments	(5,516)	(10,131)	(16,056)	13,581
Provision for other credit losses	(175)	1,121	(606)	1,121
Provision for credit losses	(9,675)	17,682	(38,124)	146,890
Net interest income after provision for credit losses	171,336	144,856	526,614	327,407
Noninterest income
Service charges on deposit accounts	11,486	10,914	33,322	32,680
Mortgage banking activity	56,460	138,627	225,177	278,885
Other service charges, commissions and fees	1,154	1,039	3,226	2,949
Net gain on securities	530	0	519	5
Other noninterest income	6,932	8,438	21,531	19,838
Total noninterest income	76,562	159,018	283,775	334,357
Noninterest expense
Salaries and employee benefits	79,671	96,698	261,161	267,812
Occupancy and equipment	11,979	13,805	34,572	39,640
Data processing and communications expenses	10,681	12,226	34,442	34,694
Credit resolution-related expenses	377	802	1,546	3,950
Advertising and marketing	2,676	966	6,053	4,779
Amortization of intangible assets	3,387	4,190	11,578	15,422
Merger and conversion charges	183	(44)	183	1,391
Other noninterest expenses	28,242	25,049	72,220	79,825
Total noninterest expense	137,196	153,692	421,755	447,513
Income (loss) before income tax expense	110,702	150,182	388,634	214,251
Income tax expense	29,022	34,037	93,665	46,548
Net income	81,680	116,145	294,969	167,703
Other comprehensive income (loss)
Net unrealized holding gains (losses) arising during period on investment securities available-for-sale, net of tax expense (benefit) of $(834), $(663), $(3,089) and $5,080	(3,139)	(2,494)	(11,620)	19,110
Net unrealized gains on cash flow hedge during the period, net of tax benefit of $0, $35, $0 and $39	0	133	0	147
Total other comprehensive income (loss)	(3,139)	(2,361)	(11,620)	19,257
Comprehensive income	$ 78,541	$ 113,784	$ 283,349	$ 186,960
Basic earnings per common share (in dollars per share)	$ 1.18	$ 1.68	$ 4.25	$ 2.42
Diluted earnings per common share (in dollars per share)	$ 1.17	$ 1.67	$ 4.23	$ 2.42
Weighted average common shares outstanding
Basic (in shares)	69,440	69,231	69,445	69,243
Diluted (in shares)	69,756	69,346	69,772	69,403