Loans - Allowance for credit loss activity (Details) - USD ($) $ in Thousands	3 Months Ended			9 Months Ended
	Sep. 30, 2020		Sep. 30, 2019	Sep. 30, 2020		Sep. 30, 2019
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning Allowance	$ 88,555		$ 28,934	$ 31,243		$ 28,331
Impact of ASC 326 Adoption				2,354
Acquisition related allowance for credit loss (PCD)				7,698
Charge-Offs	(4,219)		(191)	(4,948)		(861)
Recoveries	923		180	3,258		959
Provisions	3,658	[1]	1,327	49,312	[1],[2]	1,821
Ending Allowance	88,917		30,250	88,917		30,250
One To Four Family Residential Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning Allowance				2,867		2,881
Impact of ASC 326 Adoption				1,765
Acquisition related allowance for credit loss (PCD)				1,077
Charge-Offs				(257)		(257)
Recoveries				223		176
Provisions				12,493	[1],[2]	138
Ending Allowance	18,168		2,938	18,168		2,938
Residential Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning Allowance	23,783		2,793
Charge-Offs			(74)
Recoveries	7		6
Provisions	(5,622)	[1]	213
Ending Allowance	18,168		2,938	18,168		2,938
Commercial Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning Allowance	44,057		15,251	16,302		15,142
Impact of ASC 326 Adoption				3,682
Acquisition related allowance for credit loss (PCD)				4,053
Charge-Offs	(4,172)			(4,237)		(15)
Recoveries	581		61	1,110		450
Provisions	8,109	[1]	883	27,665	[1],[2]	618
Ending Allowance	48,575		16,195	48,575		16,195
Construction Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning Allowance	1,137		887	996		682
Impact of ASC 326 Adoption				(223)
Charge-Offs				(1)
Provisions	1,352	[1]	216	1,717	[1],[2]	421
Ending Allowance	2,489		1,103	2,489		1,103
Home Equity and Improvement [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning Allowance	4,216		1,763	1,700		2,026
Impact of ASC 326 Adoption				(521)
Acquisition related allowance for credit loss (PCD)				248
Charge-Offs	(12)		(12)	(98)		(109)
Recoveries	41		77	177		161
Provisions	148	[1]	(76)	2,887	[1],[2]	(326)
Ending Allowance	4,393		1,752	4,393		1,752
Commercial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning Allowance	11,839		7,888	9,003		7,281
Impact of ASC 326 Adoption				(2,263)
Acquisition related allowance for credit loss (PCD)				2,272
Charge-Offs			(25)	(133)		(225)
Recoveries	266		30	1,602		136
Provisions	1,139	[1]	(5)	2,763	[1],[2]	696
Ending Allowance	13,244		7,888	13,244		7,888
Consumer Finance [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning Allowance	3,523		352	375		319
Impact of ASC 326 Adoption				(86)
Acquisition related allowance for credit loss (PCD)				48
Charge-Offs	(35)		(80)	(222)		(255)
Recoveries	28		6	146		36
Provisions	(1,468)	[1]	96	1,787	[1],[2]	274
Ending Allowance	$ 2,048		$ 374	$ 2,048		$ 374

[1] Allowance/provision are not comparable to prior periods due to the adoption of CECL.

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