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, 2011	$ 141,800	$ 165,518	$ 0	$ 5,290		$ (3,120)	$ (25,888)
Beginning balance, units at Dec. 31, 2011		55,346
Weighted average limited partner units outstanding	55,473
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Limited partnership unit options exercised		15
Issuance of limited partnership units as compensation		158
Net income	111,595	111,594	1
Partnership distribution declared ($1.20 per limited partnership unit)		(66,565)
Expense recognized for limited partnership unit options		304
Tax effect of units involved in option exercises and treasury unit transactions		(454)
Issuance of limited partnership units as compensation		2,400
Current period activity, net of tax $126 at Sep. 30, 2012	(1,798)						(1,798)
Ending balance, value at Sep. 30, 2012	186,031	212,797	1	5,290	(32,057)	(4,371)	(27,686)
Current period activity, net of tax $718 at Sep. 30, 2012	$ (1,251)					$ (1,251)
Ending balance, units at Sep. 30, 2012		55,519