8. Other Income and Expenses (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Interest and investment income	$ (16,200)	$ (12,000)	$ (18,300)	$ (13,100)
Net realized loss (gain) on investments	100	200	200	(100)
Gain on sale of land	0	0	(4,100)	0
Gain on divestiture of a product line	0	0	(5,100)	0
Other Nonoperating Expense	200	400	300	800
Nonoperating Income (Expense)	$ (15,858)	$ (11,382)	$ (27,003)	$ (12,425)