Employee Retirement and Profit Sharing Plans - Fair Values by Category of Inputs (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets at end of year	$ 344,760	$ 282,183
U.S. large-cap stocks (as a percent)	90.00%
International stocks (as a percent)	10.00%
Equity Securities, Common Stock
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets at end of year	$ 364	275
Equity Securities Index Funds U S Equities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets at end of year	98,759	112,329
Equity Securities Index Funds Equity Funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets at end of year	7,675	6,204
Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets at end of year	106,798	118,808
Fixed Income, Bond Funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets at end of year	233,628	157,361
Fixed Income Diversified Funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets at end of year	2,700	3,930
Fixed Income
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets at end of year	236,328	161,291
Short-term Investment Funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets at end of year	1,634	1,921
Cash Equivalents
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets at end of year	1,634	1,921
Partnerships/ Joint Ventures
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets at end of year		163
Other Investments
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets at end of year		163
Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets at end of year	364	275
Level 1 | Equity Securities, Common Stock
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets at end of year	364	275
Level 1 | Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets at end of year	364	275
Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets at end of year	341,696	277,815
Level 2 | Equity Securities Index Funds U S Equities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets at end of year	98,759	112,329
Level 2 | Equity Securities Index Funds Equity Funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets at end of year	7,675	6,204
Level 2 | Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets at end of year	106,434	118,533
Level 2 | Fixed Income, Bond Funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets at end of year	233,628	157,361
Level 2 | Fixed Income Diversified Funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets at end of year	0
Level 2 | Fixed Income
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets at end of year	233,628	157,361
Level 2 | Short-term Investment Funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets at end of year	1,634	1,921
Level 2 | Cash Equivalents
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets at end of year	1,634	1,921
Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets at end of year	2,700	4,093	$ 4,202
Level 3 | Fixed Income Diversified Funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets at end of year	2,700	3,930	3,929
Level 3 | Fixed Income
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets at end of year	2,700	3,930
Level 3 | Partnerships/ Joint Ventures
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets at end of year	$ 0	163	$ 273
Level 3 | Other Investments
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets at end of year		$ 163