Employee Benefits (Changes in Funded Status of Plan - Other Postretirment Benefit Plans) (Details) - Other Postretirement Benefit Plan - USD ($) $ in Thousands			12 Months Ended
		Jan. 01, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Change in projected benefit obligation:
Benefit obligation at end of prior year		$ 92,643	$ 100,700	$ 92,847
Service cost			3,454	2,845	$ 3,843
Interest cost			4,035	4,463	5,156
Actuarial loss (gain)			(11,423)	3,465
Amendment	[1]		(824)	0
Benefits paid			(4,544)	(4,031)
Retiree contributions			1,245	1,111
Benefit obligation at end of year			92,643	100,700	92,847
Change in plan assets:
Fair value of plan assets at end of prior year		$ 38,090	41,358	42,192
Actual return (loss) on plan assets			(469)	2,086
Employer contribution			500	0
Benefits paid			(4,544)	(4,031)
Retiree contributions			1,245	1,111
Fair value of plan assets at end of year			38,090	41,358	$ 42,192
Funded status at end of year			$ (54,553)	$ (59,342)
Subsequent Event
Change in plan assets:
Defined Benefit Plan Amendment Effective Date		Jan. 01, 2016

[1] Amendment relates to modification of the Company's Other Post-retirement Benefit Plan which increased mail order co-payments for post age 65 medications. The plan change was approved in 2015. The amendment became effective January 1, 2016