Consolidated Statements of Income and Comprehensive Income (unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Interest income
Interest and fees on loans	$ 167,761	$ 175,345	$ 338,918	$ 346,587
Interest on taxable securities	5,244	9,347	11,362	19,429
Interest on nontaxable securities	139	157	280	314
Interest on deposits in other banks and federal funds sold	607	169	1,141	1,456
Total interest income	173,751	185,018	351,701	367,786
Interest expense
Interest on deposits	5,775	14,273	12,573	38,375
Interest on other borrowings	6,124	6,931	12,299	17,652
Total interest expense	11,899	21,204	24,872	56,027
Net interest income	161,852	163,814	326,829	311,759
Provision for loan losses	(899)	68,449	(17,478)	105,496
Provision for unfunded commitments	1,299	19,712	(10,540)	23,712
Provision for other credit losses	(258)	0	(431)	0
Provision for credit losses	142	88,161	(28,449)	129,208
Net interest income after provision for credit losses	161,710	75,653	355,278	182,551
Noninterest income
Service charges on deposit accounts	11,007	9,922	21,836	21,766
Mortgage banking activity	70,231	104,925	168,717	140,258
Other service charges, commissions and fees	1,056	949	2,072	1,910
Net gain (loss) on securities	1	14	(11)	5
Other noninterest income	6,945	5,150	14,599	11,400
Total noninterest income	89,240	120,960	207,213	175,339
Noninterest expense
Salaries and employee benefits	85,505	95,168	181,490	171,114
Occupancy and equipment	10,812	13,807	22,593	25,835
Data processing and communications expenses	11,877	10,514	23,761	22,468
Credit resolution-related expenses	622	950	1,169	3,148
Advertising and marketing	1,946	1,455	3,377	3,813
Amortization of intangible assets	4,065	5,601	8,191	11,232
Merger and conversion charges	0	895	0	1,435
Other noninterest expenses	20,934	27,378	43,978	54,776
Total noninterest expense	135,761	155,768	284,559	293,821
Income (loss) before income tax expense	115,189	40,845	277,932	64,069
Income tax expense	26,862	8,609	64,643	12,511
Net income	88,327	32,236	213,289	51,558
Other comprehensive income (loss)
Net unrealized holding gains (losses) arising during period on investment securities available-for-sale, net of tax expense (benefit) of $(283), $(13), $(2,255) and $5,743	(1,066)	(49)	(8,481)	21,604
Net unrealized gains on cash flow hedge during the period, net of tax benefit of $0, $30, $0 and $4	0	111	0	14
Total other comprehensive income (loss)	(1,066)	62	(8,481)	21,618
Comprehensive income	$ 87,261	$ 32,298	$ 204,808	$ 73,176
Basic earnings per common share (in dollars per share)	$ 1.27	$ 0.47	$ 3.07	$ 0.74
Diluted earnings per common share (in dollars per share)	$ 1.27	$ 0.47	$ 3.06	$ 0.74
Weighted average common shares outstanding
Basic (in shares)	69,497	69,192	69,448	69,235
Diluted (in shares)	69,792	69,293	69,765	69,413