Income Taxes (Narrative) (Details) - USD ($)	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Valuation Allowance [Line Items]
Operating Loss Carryforwards	$ 0								$ 0
Income tax expense	4,263,000	$ 2,636,000	$ 1,136,000	$ (156,000)	$ 2,767,000	$ 3,281,000	$ 2,238,000	$ 3,377,000	7,879,000	$ 11,663,000	$ 8,686,000
Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount									0	0	(805,000)
Gain (Loss) on Sale of Equity Investments									680,000	787,000,000	413,000,000
Deferred Tax Liabilities, Net					921,000					921,000
Federal Income Tax Expense on Securities Transactions										34,000
Investments, Owned, Federal Income Tax Note [Line Items]
Value of Equity Trading Securities Sold for Capital Gain											6,700,000
Available-for-sale securities
Valuation Allowance [Line Items]
Deferred Tax Liabilities, Investments	$ 3,886,000				$ 1,410,000				3,886,000	1,410,000
Pension benefits
Valuation Allowance [Line Items]
Employer contributions									$ 0	$ 0	$ 3,200,000