Restatement of Previously Issued Financial Statements (Cash Flow) (Details) - USD ($) $ in Thousands	3 Months Ended				6 Months Ended			12 Months Ended				39 Months Ended
	Jun. 28, 2015	Mar. 29, 2015		Jun. 29, 2014	Jun. 28, 2015		Jun. 29, 2014	Dec. 31, 2014		Dec. 31, 2013	Dec. 31, 2012	Mar. 31, 2015
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Net income	$ 64,629			$ 59,544	$ 150,317		$ 109,885
Asset impairment					2,462		791
Depreciation, depletion and amortization					104,024		95,516
Gain on reversal of Fox River environmental reserves					(32,543)		0
Share-based compensation expense					4,353		9,245
Equity in earnings of affiliates	(3,269)			(3,126)	(4,315)		(4,602)
Cash dividends from affiliated companies					1,150		3,527
Gain on disposition of assets					(7,210)		(940)
Pension and postretirement plan expense					27,965		19,431
Pension and postretirement plan contributions					(25,118)		(53,592)
Tax effect of share-based compensation exercises					3,513		2,030
Excess tax benefit of share-based compensation					(3,521)		(2,130)
Net (decrease)/increase in deferred taxes					(9,487)		4,908
Trade accounts receivable					(33,084)		(84,127)
Inventories					(18,020)		(10,666)
Payable to suppliers					14,913		18,815
Prepaid expenses					(7,014)		(10,624)
Accrued expenses					5,941		17,619
Income taxes payable and other income tax items					417		9,880
Fox River environmental reserve spending					(720)		(14,934)
Other assets and liabilities					(941)		(4,498)
Net cash provided by operating activities					173,082		105,534
Purchase of property, plant and equipment					(86,713)		(85,886)
Cost of acquisitions, net of cash acquired					(15,697)		(10,964)
Proceeds from the sale of assets					31,006		3,588
Investment in affiliates and other, net					(2,775)		138
Net cash used in investing activities					(74,179)		(93,124)
Proceeds from issuance of debt					40,240		26,946
Principal repayment of debt					(23,575)		(23,411)
Net increase in commercial paper					0		51,000
Net (decrease)/increase in outstanding checks					(1,204)		3,915
Excess tax benefit of share-based compensation					3,521		2,130
Cash dividends					(67,379)		(64,353)
Shares acquired					(7,728)		(29,739)
Shares issued					1,310		2,508
Net cash used in financing activities					(54,815)		(31,004)
Effects of Exchange Rate Changes on Cash					12,519		807
Net Increase/(Decrease) in Cash and Cash Equivalents					56,607		(17,787)
Cash and cash equivalents at beginning of period		$ 161,168	[1]		161,168	[1]	217,567	$ 217,567
Cash and cash equivalents at end of period	$ 217,775			199,780	$ 217,775		199,780	161,168	[1]	$ 217,567
Overstatement of Operating Results of a Packaging Services Center in Mexico [Member] | Previously Reported [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Net income				61,609			113,834
Asset impairment							791
Depreciation, depletion and amortization							95,516
Gain on reversal of Fox River environmental reserves							0
Share-based compensation expense							9,245
Equity in earnings of affiliates				(3,126)			(4,602)
Cash dividends from affiliated companies							3,527
Gain on disposition of assets							(940)
Pension and postretirement plan expense							19,431
Pension and postretirement plan contributions							(53,592)
Tax effect of share-based compensation exercises							2,030
Excess tax benefit of share-based compensation							(2,130)
Net (decrease)/increase in deferred taxes							5,584
Trade accounts receivable							(84,127)
Inventories							(10,666)
Payable to suppliers							21,039
Prepaid expenses							(10,624)
Accrued expenses							10,066
Income taxes payable and other income tax items							10,584
Fox River environmental reserve spending							(14,934)
Other assets and liabilities							(4,498)
Net cash provided by operating activities							105,534
Purchase of property, plant and equipment							(85,886)
Cost of acquisitions, net of cash acquired							(10,964)
Proceeds from the sale of assets							3,588
Investment in affiliates and other, net							138
Net cash used in investing activities							(93,124)
Proceeds from issuance of debt							26,946
Principal repayment of debt							(23,411)
Net increase in commercial paper							51,000
Net (decrease)/increase in outstanding checks							3,915
Excess tax benefit of share-based compensation							2,130
Cash dividends							(64,353)
Shares acquired							(29,739)
Shares issued							2,508
Net cash used in financing activities							(31,004)
Effects of Exchange Rate Changes on Cash							807
Net Increase/(Decrease) in Cash and Cash Equivalents							(17,787)
Cash and cash equivalents at beginning of period							217,567	217,567
Cash and cash equivalents at end of period				199,780			199,780			217,567
Overstatement of Operating Results of a Packaging Services Center in Mexico [Member] | Effect of Restatement [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Net income		$ 2,139		(2,065)			(3,949)	10,817		9,758	$ 601	$ 23,315
Asset impairment							0
Depreciation, depletion and amortization							0
Gain on reversal of Fox River environmental reserves							0
Share-based compensation expense							0
Equity in earnings of affiliates				0			0
Cash dividends from affiliated companies							0
Gain on disposition of assets							0
Pension and postretirement plan expense							0
Pension and postretirement plan contributions							0
Tax effect of share-based compensation exercises							0
Excess tax benefit of share-based compensation							0
Net (decrease)/increase in deferred taxes							(676)
Trade accounts receivable							0
Inventories							0
Payable to suppliers							(2,224)
Prepaid expenses							0
Accrued expenses							7,553
Income taxes payable and other income tax items							(704)
Fox River environmental reserve spending							0
Other assets and liabilities							0
Net cash provided by operating activities							0
Purchase of property, plant and equipment							0
Cost of acquisitions, net of cash acquired							0
Proceeds from the sale of assets							0
Investment in affiliates and other, net							0
Net cash used in investing activities							0
Proceeds from issuance of debt							0
Principal repayment of debt							0
Net increase in commercial paper							0
Net (decrease)/increase in outstanding checks							0
Excess tax benefit of share-based compensation							0
Cash dividends							0
Shares acquired							0
Shares issued							0
Net cash used in financing activities							0
Effects of Exchange Rate Changes on Cash							0
Net Increase/(Decrease) in Cash and Cash Equivalents							0
Cash and cash equivalents at beginning of period							0	$ 0
Cash and cash equivalents at end of period				$ 0			$ 0			$ 0

[1] The year-end condensed consolidated balance sheet data was derived from audited financial statements, but does not include all disclosures required by accounting principles generally accepted in the United States of America.