Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Net earnings	$ 2,600	$ 7,515
Defined benefit pension and other postretirement employee benefits:
Amortization of actuarial loss included in net periodic cost, net of tax of $617 and $414	1,728	631
Amortization of prior service credit included in net periodic cost, net of tax of $(110) and $(151)	(309)	(230)	$ (230)
Other comprehensive income (loss), net of tax	1,419	401
Comprehensive income	$ 4,019	$ 7,916