Summary of Significant Accounting Policies (Accounting Standards Adopted in 2020) (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Jan. 01, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Allowance for loan loss	$ 106,246	$ 136,589	$ 218,011		$ 3,025	$ 2,271	$ 1,986	$ 1,651	$ 968
Cumulative Effect, Period of Adoption, Adjustment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Allowance for loan loss				$ 8,300