Related Party Transactions (Affiliated Commercial Mortgage Loan) (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020		Dec. 31, 2019
Related Party Transaction [Line Items]
Commercial Mortgage Loans	$ 1,677,951	[1]	$ 1,471,522
Affiliated Entity | Commercial Mortgage Loans
Related Party Transaction [Line Items]
Interest Rates	4.66%
Commercial Mortgage Loans	$ 74,005

[1] September 30, 2020 amounts include the impacts of the January 1, 2020 adoption of ASU 2016-13. See Note 2 for details.