Allowance for Credit Losses (ACL) - Disaggregated analysis of the changes in allowance for credit losses (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended		12 Months Ended
	Mar. 01, 2022	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Allowance for credit losses
Balance at beginning of period		$ 427,392	$ 319,708	$ 356,444	$ 301,807	$ 301,807
Charge-offs		(17,970)	(7,126)	(30,175)	(18,779)	(23,446)
Recoveries		4,773	8,388	12,630	15,379
Net (charge-offs) recoveries		(13,197)	1,262	(17,545)	(3,400)
Provision (recovery)		33,761	3,428	109,057	(1,464)
Balance at end of period		447,956	324,398	447,956	324,398	356,444
Unfunded Commitment
Allowance for credit losses
Provision (recovery)		1,100	20,000	4,900	22,500
Initial PCD Allowance
Allowance for credit losses
Balance at end of period			13,758		13,758
Initial Non PCD Allowance
Allowance for credit losses
Balance at end of period			13,697		13,697
Residential Mortgage Sr.
Allowance for credit losses
Balance at beginning of period		81,469	55,707	72,188	47,036	47,036
Charge-offs		(57)	(50)	(96)	(169)
Recoveries		240	376	836	1,131
Net (charge-offs) recoveries		183	326	740	962
Provision (recovery)		(4,601)	11,987	4,123	18,859
Balance at end of period		77,051	68,020	77,051	68,020	72,188
Residential Mortgage Sr. | Initial PCD Allowance
Allowance for credit losses
Balance at end of period			811		811
Residential Mortgage Sr. | Initial Non PCD Allowance
Allowance for credit losses
Balance at end of period			352		352
Residential Mortgage Jr.
Allowance for credit losses
Balance at beginning of period		392	533	405	611	611
Charge-offs					(19)
Recoveries		28	30	36	195
Net (charge-offs) recoveries		28	30	36	176
Provision (recovery)		74	(40)	53	(290)
Balance at end of period		494	523	494	523	405
Residential Mortgage Jr. | Initial Non PCD Allowance
Allowance for credit losses
Balance at end of period			26		26
HELOC
Allowance for credit losses
Balance at beginning of period		14,212	16,918	14,886	13,325	13,325
Charge-offs		(88)	(23)	(127)	(444)
Recoveries		226	3,151	1,003	3,803
Net (charge-offs) recoveries		138	3,128	876	3,359
Provision (recovery)		(1,036)	(3,980)	(2,448)	(750)
Balance at end of period		13,314	16,066	13,314	16,066	14,886
HELOC | Initial Non PCD Allowance
Allowance for credit losses
Balance at end of period			132		132
Residential Construction
Allowance for credit losses
Balance at beginning of period		8,869	7,565	8,974	4,997	4,997
Recoveries		3	2	97	7
Net (charge-offs) recoveries		3	2	97	7
Provision (recovery)		(1,643)	763	(1,842)	3,324
Balance at end of period		7,229	8,330	7,229	8,330	8,974
Residential Construction | Initial Non PCD Allowance
Allowance for credit losses
Balance at end of period			2		2
Commercial Construction and Development
Allowance for credit losses
Balance at beginning of period		55,314	27,730	45,410	37,593	37,593
Charge-offs		(8)		(10)	(4)
Recoveries		67	280	523	924
Net (charge-offs) recoveries		59	280	513	920
Provision (recovery)		9,099	3,798	18,549	(8,678)
Balance at end of period		64,472	31,808	64,472	31,808	45,410
Commercial Construction and Development | Initial PCD Allowance
Allowance for credit losses
Balance at end of period			86		86
Commercial Construction and Development | Initial Non PCD Allowance
Allowance for credit losses
Balance at end of period			1,887		1,887
Consumer
Allowance for credit losses
Balance at beginning of period		24,577	24,752	22,767	23,149	23,149
Charge-offs		(3,129)	(2,742)	(8,875)	(7,527)
Recoveries		651	573	1,755	1,765
Net (charge-offs) recoveries		(2,478)	(2,169)	(7,120)	(5,762)
Provision (recovery)		656	4,221	7,108	9,366
Balance at end of period		22,755	26,804	22,755	26,804	22,767
Consumer | Initial Non PCD Allowance
Allowance for credit losses
Balance at end of period			51		51
Multifamily
Allowance for credit losses
Balance at beginning of period		9,767	2,458	3,684	4,921	4,921
Provision (recovery)		2,825	666	8,908	(2,223)
Balance at end of period		12,592	3,124	12,592	3,124	3,684
Multifamily | Initial Non PCD Allowance
Allowance for credit losses
Balance at end of period			426		426
Municipal
Allowance for credit losses
Balance at beginning of period		745	703	849	565	565
Provision (recovery)		56	(1)	(48)	137
Balance at end of period		801	702	801	702	849
CRE Owner Occupied
Allowance for credit losses
Balance at beginning of period		70,759	64,688	58,083	61,794	61,794
Charge-offs		(91)	(1,353)	(126)	(1,802)
Recoveries		415	569	801	977
Net (charge-offs) recoveries		324	(784)	675	(825)
Provision (recovery)		1,932	(9,745)	14,257	(11,738)
Balance at end of period		73,015	54,159	73,015	54,159	58,083
CRE Owner Occupied | Initial PCD Allowance
Allowance for credit losses
Balance at end of period			2,409		2,409
CRE Owner Occupied | Initial Non PCD Allowance
Allowance for credit losses
Balance at end of period			2,519		2,519
Non Owner Occupied CRE
Allowance for credit losses
Balance at beginning of period		115,269	85,169	78,485	79,649	79,649
Charge-offs			(8)	(51)	(368)
Recoveries		511	29	951	402
Net (charge-offs) recoveries		511	21	900	34
Provision (recovery)		8,749	(8,937)	45,144	(6,127)
Balance at end of period		124,529	76,253	124,529	76,253	78,485
Non Owner Occupied CRE | Initial Non PCD Allowance
Allowance for credit losses
Balance at end of period			2,697		2,697
C & I
Allowance for credit losses
Balance at beginning of period		46,019	33,485	50,713	28,167	28,167
Charge-offs		(14,597)	(2,950)	(20,890)	(8,446)
Recoveries		2,632	3,378	6,628	6,175
Net (charge-offs) recoveries		(11,965)	428	(14,262)	(2,271)
Provision (recovery)		17,650	4,696	15,253	(3,344)
Balance at end of period		$ 51,704	38,609	$ 51,704	38,609	$ 50,713
C & I | Initial PCD Allowance
Allowance for credit losses
Balance at end of period			10,452		10,452
C & I | Initial Non PCD Allowance
Allowance for credit losses
Balance at end of period			$ 5,605		$ 5,605
Atlantic Capital
Allowance for credit losses
Charge-offs	$ (22,100)