Amount of recovery of financing receivables doubtful of collection that were previously charged off.

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Amount of direct write-downs of financing receivables charged against the allowance.

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Amount of allowance to cover probable credit losses on loans and leases. Includes carryover of or adjustments to the allowance for loan losses in connection with business combinations. Excludes allowance for loans and leases covered under loss sharing agreements.

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

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Allowance for Loan Losses Allowance Rollforward (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Loans and Leases Receivable, Allowance, Beginning of Period				$ 74,742				$ 78,077	$ 74,742	$ 78,077	$ 78,500
Provision/ (credit) for loan losses	$ 93	$ (949)	$ 453	(1,795)	$ (942)	$ (432)	$ (6,114)	(181)	(2,198)	(7,669)	(6,935)
Loans charged-off									(899)	(863)	(3,949)
Financing Receivable, Allowance for Credit Losses, Recovery									3,667	5,197	10,461
Loans and Leases Receivable, Allowance, End of Period	75,312				74,742				75,312	74,742	78,077
Commercial and industrial
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Loans and Leases Receivable, Allowance, Beginning of Period								12,751		12,751	15,814
Provision/ (credit) for loan losses											(3,424)
Loans charged-off											(2,851)
Financing Receivable, Allowance for Credit Losses, Recovery											3,212
Loans and Leases Receivable, Allowance, End of Period											12,751
Commercial real estate
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Loans and Leases Receivable, Allowance, Beginning of Period								50,412		50,412	44,215
Provision/ (credit) for loan losses											157
Loans charged-off											0
Financing Receivable, Allowance for Credit Losses, Recovery											6,040
Loans and Leases Receivable, Allowance, End of Period											50,412
Construction and land
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Loans and Leases Receivable, Allowance, Beginning of Period								3,039		3,039	6,322
Provision/ (credit) for loan losses											(4,000)
Loans charged-off											(400)
Financing Receivable, Allowance for Credit Losses, Recovery											1,117
Loans and Leases Receivable, Allowance, End of Period											3,039
Residential
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Loans and Leases Receivable, Allowance, Beginning of Period								10,449		10,449	10,544
Provision/ (credit) for loan losses											445
Loans charged-off											(605)
Financing Receivable, Allowance for Credit Losses, Recovery											65
Loans and Leases Receivable, Allowance, End of Period											10,449
Home equity
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Loans and Leases Receivable, Allowance, Beginning of Period								1,035		1,035	1,085
Provision/ (credit) for loan losses											(50)
Loans charged-off											0
Financing Receivable, Allowance for Credit Losses, Recovery											0
Loans and Leases Receivable, Allowance, End of Period											1,035
Consumer and other
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Loans and Leases Receivable, Allowance, Beginning of Period								391		391	520
Provision/ (credit) for loan losses											(63)
Loans charged-off											(93)
Financing Receivable, Allowance for Credit Losses, Recovery											27
Loans and Leases Receivable, Allowance, End of Period											391
Commercial and industrial
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Loans and Leases Receivable, Allowance, Beginning of Period				11,735				12,751	11,735	12,751
Provision/ (credit) for loan losses									4,206	(1,095)
Loans charged-off									(709)	(393)
Financing Receivable, Allowance for Credit Losses, Recovery									680	472
Loans and Leases Receivable, Allowance, End of Period	15,912				11,735				15,912	11,735	12,751
Commercial real estate
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Loans and Leases Receivable, Allowance, Beginning of Period				46,820				50,412	46,820	50,412
Provision/ (credit) for loan losses									(7,140)	(8,213)
Loans charged-off									(135)	0
Financing Receivable, Allowance for Credit Losses, Recovery									2,389	4,621
Loans and Leases Receivable, Allowance, End of Period	41,934				46,820				41,934	46,820	50,412
Construction and land
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Loans and Leases Receivable, Allowance, Beginning of Period				4,949				3,039	4,949	3,039
Provision/ (credit) for loan losses									1,073	1,885
Loans charged-off									0	0
Financing Receivable, Allowance for Credit Losses, Recovery									0	25
Loans and Leases Receivable, Allowance, End of Period	6,022				4,949				6,022	4,949	3,039
Residential
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Loans and Leases Receivable, Allowance, Beginning of Period				9,773				10,449	9,773	10,449
Provision/ (credit) for loan losses									(160)	(665)
Loans charged-off									(16)	(58)
Financing Receivable, Allowance for Credit Losses, Recovery									429	47
Loans and Leases Receivable, Allowance, End of Period	10,026				9,773				10,026	9,773	10,449
Home equity
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Loans and Leases Receivable, Allowance, Beginning of Period				835				1,035	835	1,035
Provision/ (credit) for loan losses									448	(200)
Loans charged-off									0	0
Financing Receivable, Allowance for Credit Losses, Recovery									1	0
Loans and Leases Receivable, Allowance, End of Period	1,284				835				1,284	835	1,035
Consumer and other
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Loans and Leases Receivable, Allowance, Beginning of Period				$ 630				$ 391	630	391
Provision/ (credit) for loan losses									(625)	619
Loans charged-off									(39)	(412)
Financing Receivable, Allowance for Credit Losses, Recovery									168	32
Loans and Leases Receivable, Allowance, End of Period	$ 134				$ 630				$ 134	$ 630	$ 391