Long-Term Debt (Narrative) (Detail) - USD ($)			6 Months Ended
		Apr. 02, 2018	Jun. 30, 2018	Feb. 28, 2018	Dec. 31, 2017	Apr. 20, 2017
Debt Instrument [Line Items]
Long term debt			$ 3,809,600,000		$ 3,926,321,000
Cash and cash equivalents			145,801,000		433,815,000
Credit Agreement [Member]
Debt Instrument [Line Items]
Credit facility			$ 3,200,000,000
Covenant decription			During the continuance of an event of default, the Lenders may take a number of actions, including, among others, declaring the entire amount then outstanding under the Credit Agreement to be due and payable. The Credit Agreement includes a financial covenant limiting, as of the last day of each fiscal quarter, the ratio of (a) (i) Consolidated Total Funded Debt (as defined in the Credit Agreement) as of such date less (ii) the sum of cash and cash equivalents of the Company and its subsidiaries on a dollar-for-dollar basis as of such date in excess of $50,000 up to a maximum of $200,000 (such that the maximum amount of reduction pursuant to this calculation does not exceed $150,000) to (b) Consolidated EBITDA (as defined in the Credit Agreement), measured for the preceding 12 months (the "Leverage Ratio"), to not more than 3.50 to 1.00 (or 3.75 to 1.00 during material acquisition periods, subject to certain limitations). The Credit Agreement also includes a financial covenant requiring the ratio of Consolidated EBIT (as defined in the Credit Agreement) to Consolidated Total Interest Expense (as defined in the Credit Agreement), in each case, measured for the preceding 12 months, to be not less than 2.75 to 1.00.
Maturity date			Mar. 21, 2023
Credit Agreement [Member] | Letter of Credit [Member]
Debt Instrument [Line Items]
Credit facility			$ 500,000,000
Credit Agreement [Member] | Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Credit facility			1,562,500,000
Long term debt	[1]		195,166,000		192,101,000
Credit Agreement [Member] | Term Loan Facility [Member]
Debt Instrument [Line Items]
Credit facility			$ 1,637,500,000
Credit Agreement [Member] | Minimum [Member]
Debt Instrument [Line Items]
Required interest coverage ratio			2.75
Credit Agreement [Member] | Minimum [Member] | Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Interest rate	[1]		2.77%
Credit Agreement [Member] | Maximum [Member]
Debt Instrument [Line Items]
Reguired leverage ratio during material acquisition period			3.75
Required leverage ratio			3.50
Credit Agreement [Member] | Maximum [Member] | Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Interest rate	[1]		3.58%
Credit Agreement [Member] | Maximum [Member] | Swing Line Loans [Member]
Debt Instrument [Line Items]
Swing line loans			$ 75,000,000
2016 Master Note Purchase Agreement [Member]
Debt Instrument [Line Items]
Maximum limit of aggregate principal amount of notes outstanding			1,500,000,000
Tax-exempt Bonds [Member]
Debt Instrument [Line Items]
Long term debt	[1]		$ 36,430,000		95,430,000
Tax-exempt Bonds [Member] | Minimum [Member]
Debt Instrument [Line Items]
Interest rate	[1]		1.41%
Tax-exempt Bonds [Member] | Maximum [Member]
Debt Instrument [Line Items]
Interest rate	[1]		1.62%
Notes Payable to Sellers and Other Third Parties [Member]
Debt Instrument [Line Items]
Long term debt	[1]		$ 15,504,000		26,290,000
Notes Payable to Sellers and Other Third Parties [Member] | Minimum [Member]
Debt Instrument [Line Items]
Interest rate	[1]		2.75%
Notes Payable to Sellers and Other Third Parties [Member] | Maximum [Member]
Debt Instrument [Line Items]
Interest rate	[1]		24.81%
Pennsylvania Economic Development Corporation IRB Bond [Member]
Debt Instrument [Line Items]
Principal balance				$ 35,000,000
Mission Economic Development Corporation IRB Bond [Member]
Debt Instrument [Line Items]
Principal balance				$ 24,000,000
Senior Notes [Member] | 2016 Master Note Purchase Agreement [Member]
Debt Instrument [Line Items]
Aggregate principal amount			$ 1,150,000,000
Senior Notes [Member] | Assumed 2008 Note Purchase Agreement [Member]
Debt Instrument [Line Items]
Maximum limit of aggregate principal amount of notes outstanding			1,250,000,000
Aggregate principal amount			$ 775,000,000
Senior Notes [Member] | Senior Notes due 2018 [Member]
Debt Instrument [Line Items]
Long term debt					50,000,000
Maturity date			Apr. 02, 2018
Interest rate		4.00%
Maturities of senior notes		$ 50,000
Senior Notes [Member] | Senior Notes due 2019 [Member]
Debt Instrument [Line Items]
Long term debt			$ 175,000,000		175,000,000
Interest rate			5.25%
Aggregate principal amount			$ 175,000,000
Debt instrument maturity date year			2019
Senior Notes [Member] | Senior Notes due 2021 [Member]
Debt Instrument [Line Items]
Long term debt			$ 100,000,000		100,000,000
Interest rate			4.64%
Aggregate principal amount			$ 100,000,000
Debt instrument maturity date year			2021
Senior Notes [Member] | New Senior Notes due 2021 [Member]
Debt Instrument [Line Items]
Long term debt			$ 150,000,000		150,000,000
Maturity date			Jun. 01, 2021
Interest rate			2.39%
Aggregate principal amount			$ 150,000,000
Senior Notes [Member] | Senior Notes due 2022 [Member]
Debt Instrument [Line Items]
Long term debt			$ 125,000,000		125,000,000
Interest rate			3.09%
Aggregate principal amount			$ 125,000,000
Debt instrument maturity date year			2022
Senior Notes [Member] | Senior Notes due 2023 [Member]
Debt Instrument [Line Items]
Long term debt			$ 200,000,000		200,000,000
Maturity date			Jun. 01, 2023
Interest rate			2.75%
Aggregate principal amount			$ 200,000,000
Senior Notes [Member] | Senior Notes due 2024 [Member]
Debt Instrument [Line Items]
Long term debt			$ 150,000,000		150,000,000
Maturity date			Apr. 20, 2024
Interest rate			3.24%
Aggregate principal amount						$ 150,000,000
Senior Notes [Member] | Senior Notes due 2025 [Member]
Debt Instrument [Line Items]
Long term debt			$ 375,000,000		375,000,000
Interest rate			3.41%
Aggregate principal amount			$ 375,000,000
Debt instrument maturity date year			2025
Senior Notes [Member] | Senior Notes due 2026 [Member]
Debt Instrument [Line Items]
Long term debt			$ 400,000,000		400,000,000
Maturity date			Jun. 01, 2026
Interest rate			3.03%
Aggregate principal amount			$ 400,000,000
Senior Notes [Member] | Senior Notes due 2027 [Member]
Debt Instrument [Line Items]
Long term debt			$ 250,000,000		250,000,000
Maturity date			Apr. 20, 2027
Interest rate			3.49%
Aggregate principal amount						250,000,000
Senior Notes [Member] | 2017 A Senior Notes [Member]
Debt Instrument [Line Items]
Aggregate principal amount			$ 400,000,000			$ 400,000,000
Term Loan Facility [Member] | Credit Agreement [Member]
Debt Instrument [Line Items]
Long term debt	[1]		$ 1,637,500,000		1,637,500,000
Interest rate	[1]		3.19%
Term Loan Facility [Member] | Credit Agreement [Member] | Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Credit facility maximum increase to borrowing capacity			$ 500,000,000
Maximum amount of increase in commitments under the credit agreement			3,700,000,000
Credit Agreement Covenant [Member] | Credit Agreement [Member] | Minimum [Member]
Debt Instrument [Line Items]
Cash and cash equivalents			50,000,000
Credit Agreement Covenant [Member] | Credit Agreement [Member] | Maximum [Member]
Debt Instrument [Line Items]
Cash and cash equivalents			200,000,000
Credit Agreement Covenant [Member] | Other Assets [Member] | Credit Agreement [Member] | Maximum [Member]
Debt Instrument [Line Items]
Cash and cash equivalents			$ 150,000,000
Base Rate [Member] | Canadian Prime Rate Loans and Swing Line Loans [Member] | Minimum [Member]
Debt Instrument [Line Items]
Margin rate for loans			0.00%
Base Rate [Member] | Canadian Prime Rate Loans and Swing Line Loans [Member] | Maximum [Member]
Debt Instrument [Line Items]
Margin rate for loans			0.50%
LIBOR [Member] | Credit Agreement [Member] | Term Loan Facility [Member]
Debt Instrument [Line Items]
Long term debt			$ 1,637,500,000		$ 1,637,500,000
Interest rate			3.19%		2.77%
LIBOR [Member] | Drawing Fees for Bankers' Acceptance and BA Loans and Letter of Credit [Member] | Minimum [Member]
Debt Instrument [Line Items]
Margin rate for loans			1.00%
LIBOR [Member] | Drawing Fees for Bankers' Acceptance and BA Loans and Letter of Credit [Member] | Maximum [Member]
Debt Instrument [Line Items]
Margin rate for loans			1.50%
Canadian Prime Rate [Member] | Credit Agreement [Member] | Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Credit facility outstanding			$ 9,113,000		$ 16,739,000
Interest rate applicable			3.58%		3.45%
Canadian Bankers Acceptance Loan [Member] | Credit Agreement [Member] | Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Credit facility outstanding			$ 186,053,000		$ 175,362,000
Interest rate applicable			2.77%		2.64%

[1] Interest rates represent the interest rates incurred at June 30, 2018