Loans - Allowance for credit loss activity (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning Allowance	$ 71,367	$ 88,555	$ 82,079	$ 31,243
Impact of ASC 326 Adoption				2,354
Acquisition related allowance for credit loss (PCD)				7,698
Charge-Offs	(618)	(4,219)	(1,440)	(4,948)
Recoveries	874	923	2,127	3,258
Provisions	1,594	3,658	(9,549)	49,312	[1]
Ending Allowance	73,217	88,917	73,217	88,917
One To Four Family Residential Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning Allowance	15,268	23,783	17,534	2,867
Impact of ASC 326 Adoption				1,765
Acquisition related allowance for credit loss (PCD)				1,077
Charge-Offs	(27)		(29)	(257)
Recoveries	75	7	165	223
Provisions	(1,567)	(5,622)	(3,921)	12,493	[1]
Ending Allowance	13,749	18,168	13,749	18,168
Commercial Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning Allowance	34,461	44,057	43,417	16,302
Impact of ASC 326 Adoption				3,682
Acquisition related allowance for credit loss (PCD)				4,053
Charge-Offs	(84)	(4,172)	(689)	(4,237)
Recoveries	143	581	332	1,110
Provisions	(428)	8,109	(8,968)	27,665	[1]
Ending Allowance	34,092	48,575	34,092	48,575
Construction Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning Allowance	2,739	1,137	2,741	996
Impact of ASC 326 Adoption				(223)
Charge-Offs				(1)
Recoveries			12
Provisions	882	1,352	868	1,717	[1]
Ending Allowance	3,621	2,489	3,621	2,489
Home Equity and Improvement [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning Allowance	4,988	4,216	4,739	1,700
Impact of ASC 326 Adoption				(521)
Acquisition related allowance for credit loss (PCD)				248
Charge-Offs	(47)	(12)	(50)	(98)
Recoveries	23	41	217	177
Provisions	(276)	148	(218)	2,887	[1]
Ending Allowance	4,688	4,393	4,688	4,393
Commercial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning Allowance	12,211	11,839	11,665	9,003
Impact of ASC 326 Adoption				(2,263)
Acquisition related allowance for credit loss (PCD)				2,272
Charge-Offs	(375)		(445)	(133)
Recoveries	576	266	1,279	1,602
Provisions	3,016	1,139	2,929	2,763	[1]
Ending Allowance	15,428	13,244	15,428	13,244
Consumer Finance [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning Allowance	1,700	3,523	1,983	375
Impact of ASC 326 Adoption				(86)
Acquisition related allowance for credit loss (PCD)				48
Charge-Offs	(85)	(35)	(227)	(222)
Recoveries	57	28	122	146
Provisions	(33)	(1,468)	(239)	1,787	[1]
Ending Allowance	$ 1,639	$ 2,048	$ 1,639	$ 2,048

[1] Provision for the nine months ended September 30, 2020, includes $25.9 million as a result of the Merger with UCFC.