Retirement Plans - Funded Status of the Defined Benefit Plans (Detail) - USD ($) $ in Thousands		12 Months Ended
	Sep. 30, 2015	Dec. 30, 2017	Dec. 31, 2016	Jan. 02, 2016
Change in benefit obligation:
Curtailment	$ (73,000)
Change in plan assets:
Fair value of plan assets at beginning of period		$ 799,166
Fair value of plan assets at end of period		851,283	$ 799,166
Net funded status		(125,012)	(167,068)	$ (120,545)
Amounts recognized in the consolidated balance sheets consist of the following:
Accrued benefit obligation—noncurrent		(130,511)	(172,895)
Pension Benefits [Member]
Change in benefit obligation:
Benefit obligation at beginning of period		966,234	862,886	970,469
Service cost		2,356	3,849	32,582
Interest cost		39,474	40,459	39,628
Actuarial loss (gain)		76,111	73,855	(73,282)
Curtailment				(73,191)
Prior year correction			21,917
Settlements		(87,225)	(16,002)	(15,287)
Special termination benefit				422
Benefit disbursements		(20,655)	(20,730)	(18,455)
Benefit obligation at end of period		976,295	966,234	862,886
Change in plan assets:
Fair value of plan assets at beginning of period		799,166	742,341	749,166
Return on plan assets		124,462	57,855	(21,572)
Employer contribution		35,535	35,702	48,489
Settlements		(87,225)	(16,002)	(15,287)
Benefit disbursements		(20,655)	(20,730)	(18,455)
Fair value of plan assets at end of period		851,283	799,166	742,341
Amounts recognized in the consolidated balance sheets consist of the following:
Accrued benefit obligation—current		(598)	(549)	(546)
Accrued benefit obligation—noncurrent		(124,414)	(166,519)	(119,999)
Net amount recognized in the consolidated balance sheets		(125,012)	(167,068)	(120,545)
Amounts recognized in accumulated other comprehensive loss consist of the following:
Prior service cost		5	281	438
Net gain (loss)		198,990	221,146	147,675
Net gain (loss) recognized in accumulated other comprehensive loss		198,995	221,427	148,113
Accumulated benefit obligation		973,946	963,008	854,858
Amounts expected to be amortized from accumulated other comprehensive loss in the next fiscal year:
Net loss (gain)		3,383
Prior service cost		5
Net expected to be amortized		3,388
Other Postretirement Plans [Member]
Change in benefit obligation:
Benefit obligation at beginning of period		6,952	6,974	6,789
Service cost		35	37	37
Interest cost		283	296	264
Employee contributions		195	204	209
Actuarial loss (gain)		(181)	174	(1,035)
Plan amendment				1,291
Benefit disbursements		(661)	(733)	(581)
Benefit obligation at end of period		6,623	6,952	6,974
Change in plan assets:
Employer contribution		466	529	372
Employee contributions		195	204	209
Benefit disbursements		(661)	(733)	(581)
Net funded status		(6,623)	(6,952)	(6,974)
Amounts recognized in the consolidated balance sheets consist of the following:
Accrued benefit obligation—current		(527)	(576)	(525)
Accrued benefit obligation—noncurrent		(6,096)	(6,376)	(6,449)
Net amount recognized in the consolidated balance sheets		(6,623)	(6,952)	(6,974)
Amounts recognized in accumulated other comprehensive loss consist of the following:
Net gain (loss)		864	825	1,064
Net gain (loss) recognized in accumulated other comprehensive loss		864	$ 825	$ 1,064
Amounts expected to be amortized from accumulated other comprehensive loss in the next fiscal year:
Net loss (gain)		(156)
Prior service cost		6
Net expected to be amortized		$ (150)