Consolidated Statements Of Cash Flows (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Statement of Cash Flows [Abstract]
Non cash net unrealized loss (gain) on investments, net of deferred tax benefit (provision)	$ (576)	$ 377	$ (2,145)
Adjustments to postretirement benefits obligation, net of deferred tax (provision) benefit	$ 0	$ (9)	$ (24)