Fair Value of Assets and Liabilities (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Document Period End Date			Sep. 30, 2020
Equity securities
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3	$ 0	$ 0	$ 0	$ 0