Schedule of Net Periodic Pension Benefit Costs (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Defined Benefit Plan [Abstract]
Service cost	$ 994	$ 1,003	$ 2,846	$ 2,930
Interest cost	568	649	1,628	1,932
Expected return on plan assets	(152)	(139)	(445)	(398)
Settlements and other	0	506	0	499
Amortization of actuarial net loss	431	330	1,225	991
Amortization of unrecognized prior service costs	16	16	46	47
Net periodic benefit cost	$ 1,857	$ 2,365	$ 5,300	$ 6,001