Allowance for Credit Losses (ACL) - Disaggregated analysis of the changes in allowance for credit losses (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
	Mar. 01, 2022	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Allowance for credit losses
Balance at beginning of period		$ 300,396	$ 406,460	$ 301,807	$ 457,309
Allowance Adjustment - FMV for ACBI merger		4,540		4,540
Adjusted CECL balance		304,936		304,936
Charge-offs		(6,163)	(5,662)	(11,653)	(9,036)
Recoveries		3,824	3,548	6,991	6,943
Net (charge-offs) recoveries		(2,339)	(2,114)	(4,662)	(2,093)
Provision (recovery)		17,111	(53,945)	(4,892)	(104,815)
Balance at end of period		319,708	350,401	319,708	350,401
Quantitative allowance
Collectively evaluated		258,437	323,558	258,437	323,558
Individually evaluated		16,932	1,885	16,932	1,885
Total quantitative allowance		275,369	325,443	275,369	325,443
Qualitative allowance		44,339	24,958	44,339	24,958
Unfunded Commitment
Allowance for credit losses
Provision (recovery)		2,200	4,800	2,000	12,400
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		46,002	63,042	47,036	63,561
Allowance Adjustment - FMV for ACBI merger		727		727
Adjusted CECL balance		46,729		46,729
Charge-offs		(61)	(69)	(119)	(189)
Recoveries		361	343	755	771
Net (charge-offs) recoveries		300	274	636	582
Provision (recovery)		8,678	(7,496)	6,872	(8,323)
Balance at end of period		55,707	55,820	55,707	55,820
Quantitative allowance
Collectively evaluated		55,203	50,424	55,203	50,424
Individually evaluated		479	88	479	88
Total quantitative allowance		55,682	50,512	55,682	50,512
Qualitative allowance		25	5,308	25	5,308
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		586	1,190	611	1,238
Adjusted CECL balance		586		586
Charge-offs				(19)
Recoveries		110	50	165	83
Net (charge-offs) recoveries		110	50	146	83
Provision (recovery)		(163)	(415)	(250)	(496)
Balance at end of period		533	825	533	825
Quantitative allowance
Collectively evaluated		533	825	533	825
Total quantitative allowance		533	825	533	825
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		13,671	16,003	13,325	16,698
Adjusted CECL balance		13,671		13,671
Charge-offs		(203)	(517)	(421)	(686)
Recoveries		395	766	652	1,183
Net (charge-offs) recoveries		192	249	231	497
Provision (recovery)		3,055	(1,702)	3,230	(2,645)
Balance at end of period		16,918	14,550	16,918	14,550
Quantitative allowance
Collectively evaluated		13,488	12,350	13,488	12,350
Individually evaluated		3,418	1,140	3,418	1,140
Total quantitative allowance		16,906	13,490	16,906	13,490
Qualitative allowance		12	1,060	12	1,060
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		5,616	3,892	4,997	4,914
Adjusted CECL balance		5,616		5,616
Recoveries		2		5	1
Net (charge-offs) recoveries		2		5	1
Provision (recovery)		1,947	596	2,561	(427)
Balance at end of period		7,565	4,488	7,565	4,488
Quantitative allowance
Collectively evaluated		7,565	4,438	7,565	4,438
Total quantitative allowance		7,565	4,438	7,565	4,438
Qualitative allowance			50		50
Residential Construction | Initial Non PCD Allowance
Allowance for credit losses
Balance at end of period		2		2
Other C&D
Allowance for credit losses
Balance at beginning of period		25,358	55,337	37,593	67,197
Adjusted CECL balance		25,358		25,358
Charge-offs			(77)	(4)	(87)
Recoveries		410	229	644	430
Net (charge-offs) recoveries		410	152	640	343
Provision (recovery)		1,962	(10,001)	(12,476)	(22,052)
Balance at end of period		27,730	45,488	27,730	45,488
Quantitative allowance
Collectively evaluated		21,572	45,472	21,572	45,472
Individually evaluated		865	16	865	16
Total quantitative allowance		22,437	45,488	22,437	45,488
Qualitative allowance		5,293		5,293
Other C&D | Initial PCD Allowance
Allowance for credit losses
Balance at end of period		86		86
Other C&D | 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		21,899	27,883	23,149	26,562
Adjusted CECL balance		21,899		21,899
Charge-offs		(2,124)	(1,486)	(4,785)	(3,635)
Recoveries		660	531	1,192	1,041
Net (charge-offs) recoveries		(1,464)	(955)	(3,593)	(2,594)
Provision (recovery)		4,317	(1,231)	5,145	1,729
Balance at end of period		24,752	25,697	24,752	25,697
Quantitative allowance
Collectively evaluated		24,752	21,195	24,752	21,195
Total quantitative allowance		24,752	21,195	24,752	21,195
Qualitative allowance			4,502		4,502
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		3,903	5,884	4,921	7,887
Adjusted CECL balance		3,903		3,903
Recoveries			3		3
Net (charge-offs) recoveries			3		3
Provision (recovery)		(1,445)	(4)	(2,889)	(2,007)
Balance at end of period		2,458	5,883	2,458	5,883
Quantitative allowance
Collectively evaluated		2,458	5,883	2,458	5,883
Total quantitative allowance		2,458	5,883	2,458	5,883
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		607	1,544	565	1,510
Adjusted CECL balance		607		607
Provision (recovery)		96	(481)	138	(447)
Balance at end of period		703	1,063	703	1,063
Quantitative allowance
Collectively evaluated		703	520	703	520
Total quantitative allowance		703	520	703	520
Qualitative allowance			543		543
CRE Owner Occupied
Allowance for credit losses
Balance at beginning of period		49,094	90,660	61,794	97,104
Allowance Adjustment - FMV for ACBI merger		930		930
Adjusted CECL balance		50,024		50,024
Charge-offs		(78)	(2,021)	(449)	(2,048)
Recoveries		94	131	408	464
Net (charge-offs) recoveries		16	(1,890)	(41)	(1,584)
Provision (recovery)		14,648	(13,278)	(1,993)	(20,028)
Balance at end of period		64,688	75,492	64,688	75,492
Quantitative allowance
Collectively evaluated		42,294	72,212	42,294	72,212
Individually evaluated		5,588	333	5,588	333
Total quantitative allowance		47,882	72,545	47,882	72,545
Qualitative allowance		16,806	2,947	16,806	2,947
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		96,360	107,559	79,649	124,421
Adjusted CECL balance		96,360		96,360
Charge-offs		(360)	(341)	(360)	(535)
Recoveries		304	411	373	732
Net (charge-offs) recoveries		(56)	70	13	197
Provision (recovery)		(11,135)	(17,225)	2,810	(34,214)
Balance at end of period		85,169	90,404	85,169	90,404
Quantitative allowance
Collectively evaluated		63,666	85,044	63,666	85,044
Individually evaluated		140		140
Total quantitative allowance		63,806	85,044	63,806	85,044
Qualitative allowance		21,363	5,360	21,363	5,360
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		37,300	33,466	28,167	46,217
Allowance Adjustment - FMV for ACBI merger		2,883		2,883
Adjusted CECL balance		40,183		40,183
Charge-offs		(3,337)	(1,151)	(5,496)	(1,856)
Recoveries		1,488	1,084	2,797	2,235
Net (charge-offs) recoveries		(1,849)	(67)	(2,699)	379
Provision (recovery)		(4,849)	(2,708)	(8,040)	(15,905)
Balance at end of period		33,485	30,691	33,485	30,691
Quantitative allowance
Collectively evaluated		26,203	25,195	26,203	25,195
Individually evaluated		6,442	308	6,442	308
Total quantitative allowance		32,645	25,503	32,645	25,503
Qualitative allowance		840	$ 5,188	840	$ 5,188
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)