COMPONENTS OF PENSION PLAN NET PERIODIC BENEFIT COSTS (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
	Jul. 17, 2017	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Pension Plan
Components of net periodic benefit cost:
Service cost			$ 598		$ 1,196
Interest cost		$ 1,135	1,131	$ 2,270	2,263
Expected return on plan assets		(1,251)	(1,287)	(2,503)	(2,574)
Amortization of prior service cost (1)		47		94
Amortization of net loss		772	789	1,545	1,578
Net periodic benefit cost		$ 703	$ 1,231	1,406	$ 2,463
2016 plan year
Components of net periodic benefit cost:
Employer contribution				700
2017 plan year
Components of net periodic benefit cost:
Employer contribution	$ 600			$ 600