UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF PARTNERS' EQUITY - USD ($) shares in Thousands, $ in Thousands	Total	Limited Partners [Member]	General Partner [Member]	Special L.P. Interests [Member]	AOCI Attributable to Parent [Member]
Beginning balance, units (in shares) at Dec. 31, 2017		56,359
Beginning balance, value at Dec. 31, 2017	$ 82,946	$ 81,589	$ 0	$ 5,290	$ (3,933)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	149,150	149,148	2
Partnership distribution declared	(150,852)	$ (150,850)	(2)
Issuance of limited partnership units as compensation (in shares)		82
Issuance of limited partnership units as compensation	1,235	$ 1,235
Tax effect of units involved in treasury unit transactions	(3,049)	(3,049)
Foreign currency translation adjustment	5,990				5,990
Cash flow hedging derivative activity, net of tax	6,250				6,250
Reclassification of stranded tax effect	(391)	$ 391			(391)
Ending balance, units (in shares) at Sep. 23, 2018		56,441
Ending balance, value at Sep. 23, 2018	91,670	$ 78,464	0	5,290	7,916
Beginning balance, units (in shares) at Jun. 24, 2018		56,441
Beginning balance, value at Jun. 24, 2018	(70,071)	$ (86,435)	(2)	5,290	11,076
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	213,307	213,304	3
Partnership distribution declared	(50,294)	(50,293)	(1)
Issuance of limited partnership units as compensation	1,892	1,892
Tax effect of units involved in treasury unit transactions	(4)	$ (4)
Foreign currency translation adjustment	(5,276)				(5,276)
Cash flow hedging derivative activity, net of tax	2,116				2,116
Ending balance, units (in shares) at Sep. 23, 2018		56,441
Ending balance, value at Sep. 23, 2018	91,670	$ 78,464	0	5,290	7,916
Beginning balance, units (in shares) at Dec. 31, 2018		56,564
Beginning balance, value at Dec. 31, 2018	32,416	$ 5,845	(1)	5,290	21,282
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	169,580	169,578	2
Partnership distribution declared	(157,045)	$ (157,043)	(2)
Issuance of limited partnership units as compensation (in shares)		32
Issuance of limited partnership units as compensation	4,511	$ 4,511
Tax effect of units involved in treasury unit transactions	(1,615)	$ (1,615)
Foreign currency translation adjustment	(5,128)				(5,128)
Ending balance, units (in shares) at Sep. 29, 2019		56,596
Ending balance, value at Sep. 29, 2019	42,719	$ 21,276	(1)	5,290	16,154
Beginning balance, units (in shares) at Jun. 30, 2019		56,597
Beginning balance, value at Jun. 30, 2019	(100,200)	$ (119,088)	(2)	5,290	13,600
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	189,955	189,953	2
Partnership distribution declared	(52,359)	$ (52,358)	(1)
Issuance of limited partnership units as compensation (in shares)		(1)
Issuance of limited partnership units as compensation	2,823	$ 2,823
Tax effect of units involved in treasury unit transactions	(54)	$ (54)
Foreign currency translation adjustment	2,554				2,554
Ending balance, units (in shares) at Sep. 29, 2019		56,596
Ending balance, value at Sep. 29, 2019	$ 42,719	$ 21,276	$ (1)	$ 5,290	$ 16,154