Consolidated Statements Of Cash Flows (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Statement of Cash Flows [Abstract]
Deferred tax provision related to unrealized gain (loss) on investments	$ (367)	$ (576)
Adjustments to postretirement benefits obligation, net of deferred tax benefit provision	$ 31	$ 0