Income Taxes (Narrative) (Detail) - USD ($) $ in Thousands		3 Months Ended	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 29, 2017	Dec. 31, 2016
Operating Loss Carryforwards [Line Items]
Increase (decrease) to tax expense			$ (3,057)
Deferred income tax expense			$ 68,779
Statutory income tax rate	21.00%		21.00%	35.00%	35.00%	35.00%
Non-deductible expenses, other						$ 9,048
Unrecognized tax benefits	$ 0	$ 0	$ 0	$ 0		$ 0
Net deferred income tax expense (benefit) from enactment of tax reform		(269,804)	5,572	(269,804)
Deferred income tax expense from foreign earnings transition tax		$ 62,350		62,350
Non-deductible expenses, impairment				$ 11,825
Deferred tax liabilities, undistributed earnings			961,422
Deferred tax liability not recognized, undistributed earnings of foreign subsidiaries			303,470
Undistributed earnings			$ 2,136,422
Internal Revenue Service [Member]
Operating Loss Carryforwards [Line Items]
Statutory income tax rate				35.00%		35.00%
Canada Revenue Agency [Member]
Operating Loss Carryforwards [Line Items]
Foreign Statutory income tax rate			27.00%
Operating loss carryforwards			$ 30,763
Adjustment [Member]
Operating Loss Carryforwards [Line Items]
Deferred income tax expense			$ 6,429