Credit Losses textual (Details) - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Credit Loss [Line Items]
Interest Receivable	$ 43,700,000	$ 36,000,000
Financing Receivable, Allowance for Credit Losses, Effect of Change in Method		(1,137,000)
Loans and Leases Receivable, Allowance	(146,922,000)	(113,392,000)
Financing Receivable, Allowance for Credit Loss, Period Increase (Decrease)	$ (33,500,000)
Financing Receivable, Allowance for Credit Loss, Period Increase (Decrease) by percentage	29.60%
Provision for credit losses	$ 18,205,000	52,500,000	$ 6,000,000
Off-Balance Sheet, Credit Loss, Liability	$ 1,500,000	1,200,000
Days To Be Termed As Non Accrual Loans	90 days
Tdrs Recorded Investment On Nonaccrual Status	$ 1,993,000	22,209,000
Financing Receivable, before Allowance for Credit Loss	13,540,590,000	9,371,470,000
Financing Receivable, Troubled Debt Restructuring, Subsequent Default	3,200,000	0	$ 0
Loans with active Deferrals	383,100,000	173,600,000
US Government Insured Loan Program [Member]
Credit Loss [Line Items]
Financing Receivable, before Allowance for Credit Loss	216,200,000	$ 791,900,000
Blue Hills Bancorp, Inc. [Member]
Credit Loss [Line Items]
Loans with active Deferrals	$ 194,300,000