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Amount of expense related to estimated loss from loan and lease transactions.

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Loans and allowance for credit losses - Allowance for Loan Losses by Portfolio Segment and Related Investment in Loans Net of Unearned Interest (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Jan. 01, 2020	Jan. 01, 2019
Allowance for Loan and Lease Losses [Roll Forward]
Balance at beginning of period	$ 31,139	$ 28,932
Initial adoption of ASC			$ (25,018)	$ (1,309)
Provision for loan losses	27,964	1,391
Recoveries of loans previously charged-off	334	362
Loans charged off	(2,411)	(871)
Initial allowance on loans purchased with deteriorated credit quality	669
Balance at end of period	89,141	29,814
Commercial and industrial
Allowance for Loan and Lease Losses [Roll Forward]
Balance at beginning of period	4,805	5,348
Provision for loan losses	1,829	333
Recoveries of loans previously charged-off	88	12
Loans charged off	(1,234)	(179)
Initial allowance on loans purchased with deteriorated credit quality	11
Balance at end of period	10,881	5,514
Construction
Allowance for Loan and Lease Losses [Roll Forward]
Balance at beginning of period	10,194	9,729
Provision for loan losses	10,954	28
Recoveries of loans previously charged-off	0	1
Loans charged off	0	0
Initial allowance on loans purchased with deteriorated credit quality	11
Balance at end of period	22,842	9,758
Residential real estate: \| 1-to-4 family mortgage
Allowance for Loan and Lease Losses [Roll Forward]
Balance at beginning of period	3,112	3,428
Provision for loan losses	1,664	(65)
Recoveries of loans previously charged-off	24	13
Loans charged off	(242)	(81)
Initial allowance on loans purchased with deteriorated credit quality	107
Balance at end of period	13,006	3,295
Residential real estate: \| Residential line of credit
Allowance for Loan and Lease Losses [Roll Forward]
Balance at beginning of period	752	811
Provision for loan losses	1,985	(73)
Recoveries of loans previously charged-off	15	25
Loans charged off	0	(32)
Initial allowance on loans purchased with deteriorated credit quality	3
Balance at end of period	6,213	731
Residential real estate: \| Multi-family mortgage
Allowance for Loan and Lease Losses [Roll Forward]
Balance at beginning of period	544	566
Provision for loan losses	1,444	(27)
Recoveries of loans previously charged-off	0	0
Loans charged off	0	0
Initial allowance on loans purchased with deteriorated credit quality	0
Balance at end of period	2,328	539
Commercial real estate: \| Owner occupied
Allowance for Loan and Lease Losses [Roll Forward]
Balance at beginning of period	4,109	3,132
Provision for loan losses	3,038	(121)
Recoveries of loans previously charged-off	14	87
Loans charged off	(209)	0
Initial allowance on loans purchased with deteriorated credit quality	54
Balance at end of period	9,047	3,098
Commercial real estate: \| Non-owner occupied
Allowance for Loan and Lease Losses [Roll Forward]
Balance at beginning of period	4,621	4,149
Provision for loan losses	5,935	434
Recoveries of loans previously charged-off	0	0
Loans charged off	0	0
Initial allowance on loans purchased with deteriorated credit quality	443
Balance at end of period	18,005	4,583
Consumer and other
Allowance for Loan and Lease Losses [Roll Forward]
Balance at beginning of period	3,002	1,769
Provision for loan losses	1,115	882
Recoveries of loans previously charged-off	193	224
Loans charged off	(726)	(579)
Initial allowance on loans purchased with deteriorated credit quality	40
Balance at end of period	$ 6,819	$ 2,296
Non-purchased credit deteriorated loan
Allowance for Loan and Lease Losses [Roll Forward]
Initial adoption of ASC			30,888
Non-purchased credit deteriorated loan \| Commercial and industrial
Allowance for Loan and Lease Losses [Roll Forward]
Initial adoption of ASC			5,300
Non-purchased credit deteriorated loan \| Construction
Allowance for Loan and Lease Losses [Roll Forward]
Initial adoption of ASC			1,533
Non-purchased credit deteriorated loan \| Residential real estate: \| 1-to-4 family mortgage
Allowance for Loan and Lease Losses [Roll Forward]
Initial adoption of ASC			7,920
Non-purchased credit deteriorated loan \| Residential real estate: \| Residential line of credit
Allowance for Loan and Lease Losses [Roll Forward]
Initial adoption of ASC			3,461
Non-purchased credit deteriorated loan \| Residential real estate: \| Multi-family mortgage
Allowance for Loan and Lease Losses [Roll Forward]
Initial adoption of ASC			340
Non-purchased credit deteriorated loan \| Commercial real estate: \| Owner occupied
Allowance for Loan and Lease Losses [Roll Forward]
Initial adoption of ASC			1,879
Non-purchased credit deteriorated loan \| Commercial real estate: \| Non-owner occupied
Allowance for Loan and Lease Losses [Roll Forward]
Initial adoption of ASC			6,822
Non-purchased credit deteriorated loan \| Consumer and other
Allowance for Loan and Lease Losses [Roll Forward]
Initial adoption of ASC			3,633
Purchased credit deteriorated loan
Allowance for Loan and Lease Losses [Roll Forward]
Initial adoption of ASC			558
Purchased credit deteriorated loan \| Commercial and industrial
Allowance for Loan and Lease Losses [Roll Forward]
Initial adoption of ASC			82
Purchased credit deteriorated loan \| Construction
Allowance for Loan and Lease Losses [Roll Forward]
Initial adoption of ASC			150
Purchased credit deteriorated loan \| Residential real estate: \| 1-to-4 family mortgage
Allowance for Loan and Lease Losses [Roll Forward]
Initial adoption of ASC			421
Purchased credit deteriorated loan \| Residential real estate: \| Residential line of credit
Allowance for Loan and Lease Losses [Roll Forward]
Initial adoption of ASC			(3)
Purchased credit deteriorated loan \| Residential real estate: \| Multi-family mortgage
Allowance for Loan and Lease Losses [Roll Forward]
Initial adoption of ASC			0
Purchased credit deteriorated loan \| Commercial real estate: \| Owner occupied
Allowance for Loan and Lease Losses [Roll Forward]
Initial adoption of ASC			162
Purchased credit deteriorated loan \| Commercial real estate: \| Non-owner occupied
Allowance for Loan and Lease Losses [Roll Forward]
Initial adoption of ASC			184
Purchased credit deteriorated loan \| Consumer and other
Allowance for Loan and Lease Losses [Roll Forward]
Initial adoption of ASC			$ (438)