CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
OTHER COMPREHENSIVE INCOME (LOSS)
Unrealized holding gains (losses) on investment securities, deferred income tax expense (benefit)	$ (6,429)	$ 14,688	$ (2,092)
Reclassification adjustment for net realized investment (gains) losses included in net income (loss), income tax (expense) benefit	3,895	(4,483)	(3,628)
Reclassification adjustment for amounts amortized into net periodic pension and postretirement benefit cost (income), deferred income tax (expense) benefit	(573)	(587)	(457)
Change in funded status of affiliate's pension and postretirement benefit plans, deferred income tax expense (benefit)	$ (1,022)	$ 1,507	$ (474)