Unaudited Condensed Consolidated Statement of Partners' Equity (USD $) In Thousands, unless otherwise specified	Total	Limited Partners [Member]	General Partner [Member]	Special L.P. Interests [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Accumulated Translation Adjustment [Member]	Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member]
Beginning balance, value at Dec. 31, 2013	$ 139,131	$ 148,847	$ 2	$ 5,290		$ 5	$ (15,013)
Beginning balance, units at Dec. 31, 2013		55,716
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Limited partnership unit options exercised		19
Issuance of limited partnership units as compensation		128
Net income	122,264	122,263	1
Partnership distribution declared ($2.10 per limited partnership unit)		(117,468)
Expense recognized for limited partnership unit options		668
Tax effect of units involved in option exercises and treasury unit transactions		(785)
Issuance of limited partnership units as compensation		7,632
Weighted average limited partner units outstanding	55,448
Current period activity, net of tax $6 at Sep. 28, 2014	(165)						(165)
Ending balance, value at Sep. 28, 2014	153,556	161,157	3	5,290	(12,894)	2,284	(15,178)
Current period activity, net of tax ($1,310) at Sep. 28, 2014	$ 2,279					$ 2,279
Ending balance, units at Sep. 28, 2014		55,863