9. Other Income and Expenses (Details) - USD ($) $ in Thousands	3 Months Ended			9 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Interest and investment income	$ (1,800)		$ (4,100)	$ (14,600)	$ (27,400)
Net realized (gain) loss on investments	0		(200)	(600)	(200)
Other Nonoperating (Income)			(100)		(1,000)
Other Nonoperating Expense	800			800
Equity Method Investment, Other than Temporary Impairment	0		0	4,600	1,600
Gain on Disposition of a division	0	$ (11,700)	0	(11,700)	0
Other Nonoperating Income (Expense)	$ 1,015		$ 4,367	$ 21,517	$ 26,959