Consolidated Statements Of Cash Flows (Parenthetical) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Statement of Cash Flows [Abstract]
Deferred tax provision related to unrealized gain (loss) on investments	$ (322)	$ (511)
Adjustments to postretirement benefits obligation, net of deferred tax benefit provision	$ 9	$ 0