Fair Value Measurements (Schedule of Financial Instruments Measured at Fair Value on a Recurring Basis) (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments in available-for-sale securities (at fair value)	$ 34,421	$ 41,790
State And Municipal Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments in available-for-sale securities (at fair value)	10,830	11,206
Asset-Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments in available-for-sale securities (at fair value)	5,025	5,500
Government Mortgage-Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments in available-for-sale securities (at fair value)	18,566	25,084
Recurring Basis [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments in available-for-sale securities (at fair value)	34,421	41,790
Recurring Basis [Member] | State And Municipal Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments in available-for-sale securities (at fair value)	10,830	11,206
Recurring Basis [Member] | Asset-Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments in available-for-sale securities (at fair value)	5,025	5,500
Recurring Basis [Member] | Government Mortgage-Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments in available-for-sale securities (at fair value)	18,566	25,084
Recurring Basis [Member] | Significant Other Observable Inputs Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments in available-for-sale securities (at fair value)	34,421	41,790
Recurring Basis [Member] | Significant Other Observable Inputs Level 2 [Member] | State And Municipal Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments in available-for-sale securities (at fair value)	10,830	11,206
Recurring Basis [Member] | Significant Other Observable Inputs Level 2 [Member] | Asset-Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments in available-for-sale securities (at fair value)	5,025	5,500
Recurring Basis [Member] | Significant Other Observable Inputs Level 2 [Member] | Government Mortgage-Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments in available-for-sale securities (at fair value)	$ 18,566	$ 25,084