Accounting Policies (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Jun. 30, 2021	Jan. 01, 2021	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Dec. 31, 2019
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect of adoption	$ 360,171	$ 353,033		$ 334,392	$ 325,660	$ 317,687	$ 301,728
Financing receivable, allowance for credit loss, excluding accrued interest	26,956	27,010		29,232	28,446	26,300
Off-balance sheet, credit loss, liability	1,800
Retained Earnings
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect of adoption	$ 47,936	$ 60,494		41,899	$ 33,434	$ 42,704	$ 33,218
Accounting Standards Update 2016-13
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Financing receivable, allowance for credit loss, excluding accrued interest			$ (1,300)
Off-balance sheet, credit loss, liability			1,100
Deferred tax liabilities, net			41
Cumulative Effect, Period of Adoption, Adjustment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect of adoption				120
Financing receivable, allowance for credit loss, excluding accrued interest				(1,300)
Cumulative Effect, Period of Adoption, Adjustment | Retained Earnings
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect of adoption				$ 120
Cumulative Effect, Period of Adoption, Adjustment | Accounting Standards Update 2016-13 | Retained Earnings
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect of adoption			$ 120