Employee Benefit Plans (Details) $ in Thousands			12 Months Ended
	Jan. 01, 2015 USD ($) plan_participant	Aug. 29, 2014 USD ($) plan_participant	Dec. 31, 2015 USD ($) plan_participant	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)
Change in projected benefit obligation:
Benefit obligation, January 1	$ 651,694		$ 651,694	$ 529,788
Service cost			14,175	6,523
Interest cost			26,669	26,170
Actuarial (gain) loss			(49,007)	114,694
Regular benefits paid			(22,558)	(32,134)
Amendment			0	3,342
Acquisition			339	3,311
Benefit obligation, December 31			621,312	651,694	$ 529,788
Accumulated benefit obligation			602,830	625,574
Change in plan assets:
Value of plan assets, January 1	443,962		443,962	404,335
Actual return on plan assets			(593)	43,662
Employer contributions			6,320	28,099
Benefits paid			(22,558)	(32,134)
Value of plan assets, December 31			427,131	443,962	404,335
Defined Benefit Pension Plan
Change in projected benefit obligation:
Benefit obligation, January 1	583,080		583,080	456,402
Service cost			12,851	4,952	5,527
Interest cost			23,987	23,068	20,897
Actuarial (gain) loss			(42,863)	113,410
Regular benefits paid			(16,238)	(14,752)
Benefit obligation, December 31			560,817	583,080	456,402
Accumulated benefit obligation			544,011	562,760
Change in plan assets:
Value of plan assets, January 1	443,962		443,962	404,335
Actual return on plan assets			(593)	43,662
Employer contributions			0	10,717
Benefits paid			(16,238)	(14,752)
Value of plan assets, December 31			427,131	443,962	404,335
Post-Retirement Medical Plan
Change in projected benefit obligation:
Benefit obligation, January 1	$ 12,782		12,782	11,081
Service cost			1,042	985	947
Interest cost			560	574	512
Actuarial (gain) loss			3,360	(2,092)
Regular benefits paid			(1,446)	(508)
Amendment			0	(569)
Acquisition			339	3,311
Benefit obligation, December 31			16,637	12,782	11,081
Accumulated benefit obligation			16,637	12,782
Change in plan assets:
Employer contributions			1,446	508
Benefits paid			(1,446)	(508)
Post-Retirement Medical Plan | J.P. Morgan Retirement Plan Services (RPS)
Change in projected benefit obligation:
Defined Benefit Plan, Number of Employees Covered | plan_participant		1,000
Post-Retirement Medical Plan | Putnam
Change in projected benefit obligation:
Defined Benefit Plan, Number of Employees Covered | plan_participant	150
Post-Retirement Medical Plan | Other Noncurrent Liabilities With Offset To Goodwill | J.P. Morgan Retirement Plan Services (RPS)
Change in projected benefit obligation:
Defined Benefit Plan, Benefit Obligation, Period Increase (Decrease)		$ 3,311
Post-Retirement Medical Plan | Other liabilities | Putnam
Change in projected benefit obligation:
Defined Benefit Plan, Benefit Obligation, Period Increase (Decrease)	$ 339
Supplemental Executive Retirement Plan
Change in projected benefit obligation:
Benefit obligation, January 1	$ 55,832		55,832	62,305
Service cost			282	586	1,002
Interest cost			2,122	2,528	2,548
Actuarial (gain) loss			(9,504)	3,376
Regular benefits paid			(4,874)	(16,874)
Amendment			0	3,911
Benefit obligation, December 31			43,858	55,832	$ 62,305
Accumulated benefit obligation			42,182	50,032
Change in plan assets:
Employer contributions			4,874	16,874
Benefits paid			$ (4,874)	$ (16,874)
Supplemental Executive Retirement Plan | Other Noncurrent Liabilities With Offset To Goodwill
Change in projected benefit obligation:
Defined Benefit Plan, Number of Employees Covered | plan_participant			1
Defined Benefit Plan, Benefit Obligation, Period Increase (Decrease)			$ 3,911