Fair Value Measurement (Financial Instruments Not Measured at Fair Value) (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Carrying Value
Financial assets:
Other assets	$ 27,697	$ 28,645
Financial liabilities:
Other liabilities	27,077	27,953
Carrying Value | Senior notes due 2023
Financial liabilities:
Debt instruments	250,000	250,000
Carrying Value | Mortgage loans
Financial liabilities:
Debt instruments	36,489	37,617
Carrying Value | BOLI
Financial assets:
Short-term and other investments	67,393	66,112
Carrying Value | Other investments
Financial assets:
Short-term and other investments	2,936	2,931
Fair Value
Financial assets:
Other assets	27,710	28,650
Financial liabilities:
Other liabilities	27,077	27,953
Fair Value | Senior notes due 2023
Financial liabilities:
Debt instruments	266,585	273,865
Fair Value | Mortgage loans
Financial liabilities:
Debt instruments	36,489	37,617
Fair Value | BOLI
Financial assets:
Short-term and other investments	67,393	66,112
Fair Value | Other investments
Financial assets:
Short-term and other investments	$ 2,936	$ 2,931