Summary of Changes in Fair Value of Pension Plan Assets and Liabilities Categorized as Level 3 (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 28, 2014		Dec. 29, 2013
Fair Value, Assets (Liabilities) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Fair value of pension plan liabilities at end of year	$ (4,550)	[1]	$ (11,502)	[1]
Assets, Balance at end of year	3,030,363	[1]	2,978,584	[1]
Derivative liabilities
Fair Value, Assets (Liabilities) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Fair value of pension plan liabilities at end of year	(4,550)	[1]	(11,502)	[1]
Level 3
Fair Value, Assets (Liabilities) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Assets, Balance at beginning of year	498,866	[1]	388,601
Fair value of pension plan liabilities at beginning of year	(2,008)	[1]
Actual return on plan assets relating to assets still held at report date	11,450		31,273
Actual return on plan assets relating to assets sold during the period	22,578		14,123
Purchases, sales, and settlements	48,246		64,869
Transfers in and/or out of Level 3	0	[2]	0	[2]
Fair value of pension plan liabilities at end of year	(2,008)	[1]	(2,008)	[1]
Assets, Balance at end of year	581,140	[1]	498,866	[1]
Level 3 | Derivative liabilities
Fair Value, Assets (Liabilities) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Fair value of pension plan liabilities at beginning of year	(2,008)	[1]	(2,008)
Actual return on plan assets relating to assets still held at report date	0		0
Actual return on plan assets relating to assets sold during the period	0		0
Purchases, sales, and settlements	0		0
Transfers in and/or out of Level 3	0	[2]	0	[2]
Fair value of pension plan liabilities at end of year	(2,008)	[1]	(2,008)	[1]
Mortgage Backed Securities
Fair Value, Assets (Liabilities) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Assets, Balance at end of year	4,090	[1]	4,607	[1]
Mortgage Backed Securities | Level 3
Fair Value, Assets (Liabilities) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Assets, Balance at beginning of year	397	[1]	0
Actual return on plan assets relating to assets still held at report date	0		0
Actual return on plan assets relating to assets sold during the period	2		(3)
Purchases, sales, and settlements	(304)		400
Transfers in and/or out of Level 3	0	[2]	0	[2]
Assets, Balance at end of year	95	[1]	397	[1]
Corporate bonds
Fair Value, Assets (Liabilities) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Assets, Balance at end of year	25,010	[1]	30,455	[1]
Corporate bonds | Level 3
Fair Value, Assets (Liabilities) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Assets, Balance at beginning of year	856	[1]	797
Actual return on plan assets relating to assets still held at report date	116		199
Actual return on plan assets relating to assets sold during the period	(125)		(4)
Purchases, sales, and settlements	(465)		(136)
Transfers in and/or out of Level 3	0	[2]	0	[2]
Assets, Balance at end of year	382	[1]	856	[1]
Real estate
Fair Value, Assets (Liabilities) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Assets, Balance at end of year	109,102	[1]	98,909	[1]
Real estate | Level 3
Fair Value, Assets (Liabilities) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Assets, Balance at beginning of year	98,909	[1]	97,385
Actual return on plan assets relating to assets still held at report date	279		1,865
Actual return on plan assets relating to assets sold during the period	0		0
Purchases, sales, and settlements	9,914		(341)
Transfers in and/or out of Level 3	0	[2]	0	[2]
Assets, Balance at end of year	109,102	[1]	98,909	[1]
Partnership/joint venture interests
Fair Value, Assets (Liabilities) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Assets, Balance at end of year	182,281	[1]	184,952	[1]
Partnership/joint venture interests | Level 3
Fair Value, Assets (Liabilities) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Assets, Balance at beginning of year	148,550	[1]	130,995
Actual return on plan assets relating to assets still held at report date	586		11,972
Actual return on plan assets relating to assets sold during the period	21,785		13,327
Purchases, sales, and settlements	(25,157)		(9,576)
Transfers in and/or out of Level 3	0	[2]	1,832	[2]
Assets, Balance at end of year	145,764	[1]	148,550	[1]
Hedge funds
Fair Value, Assets (Liabilities) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Assets, Balance at end of year	345,839	[1]	272,676	[1]
Hedge funds | Level 3
Fair Value, Assets (Liabilities) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Assets, Balance at beginning of year	249,991	[1]	158,924
Actual return on plan assets relating to assets still held at report date	10,469		17,613
Actual return on plan assets relating to assets sold during the period	899		803
Purchases, sales, and settlements	64,314		74,483
Transfers in and/or out of Level 3	0	[2]	(1,832)	[2]
Assets, Balance at end of year	325,673	[1]	249,991	[1]
Derivative contracts
Fair Value, Assets (Liabilities) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Assets, Balance at end of year	3,135	[1]	11,141	[1]
Derivative contracts | Level 3
Fair Value, Assets (Liabilities) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Assets, Balance at beginning of year	163	[1]	500
Actual return on plan assets relating to assets still held at report date	0		(376)
Actual return on plan assets relating to assets sold during the period	17		0
Purchases, sales, and settlements	(56)		39
Transfers in and/or out of Level 3	0	[2]	0	[2]
Assets, Balance at end of year	$ 124	[1]	$ 163	[1]

[1] We use a Dec. 31 measurement date for our retirement plans.

[2] Our policy is to recognize transfers in and transfers out as of the beginning of the reporting period.