Stockholders' Equity (Schedule of Changes in Accumulated Other Comprehensive Income (Loss) by Component) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Estimated tax benefit (provision)
Beginning balance	$ 3,000	$ 125,000	$ (22,000)
Other comprehensive income (loss) before reclassifications	159,000	(540,000)	188,000
Less: Amount reclassified from accumulated other comprehensive income (loss)	169,000	(418,000)	41,000
Net current period other comprehensive income (loss)	(10,000)	(122,000)	147,000
Ending balance	(7,000)	3,000	125,000
AOCI, after tax
Beginning balance	535,495,000	620,855,000	696,815,000
Other comprehensive income (loss) before reclassifications	(531,000)	2,245,000	(836,000)
Less: Amount reclassified from accumulated other comprehensive income (loss)	(636,000)	1,574,000	(152,000)
Net current period other comprehensive income (loss)	105,000	671,000	(684,000)
Ending balance	541,066,000	535,495,000	620,855,000
Unrealized gains (losses) on available-for-sale investments
AOCI, before tax
Beginning balance	126,000	(322,000)	(2,000)
Other comprehensive income (loss) before reclassifications	43,000	448,000	(320,000)
Less: Amount reclassified from accumulated other comprehensive income (loss)	0	0	0
Net current period other comprehensive income (loss)	43,000	448,000	(320,000)
Ending balance	169,000	126,000	(322,000)
Unrealized gains (losses) on derivatives
AOCI, before tax
Beginning balance	7,000	(338,000)	173,000
Other comprehensive income (loss) before reclassifications	(733,000)	2,337,000	(704,000)
Less: Amount reclassified from accumulated other comprehensive income (loss)	(805,000)	1,992,000	(193,000)
Net current period other comprehensive income (loss)	72,000	345,000	(511,000)
Ending balance	79,000	7,000	(338,000)
AOCI
AOCI, after tax
Beginning balance	136,000	(535,000)	149,000
Ending balance	$ 241,000	$ 136,000	$ (535,000)