Fair Value Disclosure (Schedule of Assets and Liabilities) (Details) - Fair Value, Measurements, Recurring - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Quoted prices in active markets for identical assets (level 1)
Assets:
Equity securities	$ 13,164	$ 10,120
Total assets accounted for at fair value on a recurring basis	13,164	10,120
Significant other observable inputs (level 2)
Assets:
Equity securities	0	0
Total assets accounted for at fair value on a recurring basis	0	0
Significant unobservable inputs (level 3)
Assets:
Equity securities	0	0
Total assets accounted for at fair value on a recurring basis	0	0
Estimate of Fair Value Measurement
Assets:
Equity securities	13,164	10,120
Total assets accounted for at fair value on a recurring basis	$ 13,164	$ 10,120