Consolidated Statements of Partners' Equity (USD $) In Thousands, except Per Share data, unless otherwise specified	Total	Limited Partners [Member]	General Partner [Member]	Special L.P. Interests [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Cumulative Foreign Currency Translation Adjustment [Member]	Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member]
Beginning balance, value at Dec. 31, 2009		$ 195,831	$ (1)			$ 2,422	$ (89,703)
Beginning balance, units at Dec. 31, 2009		55,234
Partnership distribution declared, per unit	$ 250
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Limited partnership unit options exercised, units		42
Issuance of limited partnership units as compensation		58
Net income (loss)	(33,052)	(33,052)	0
Partnership distribution declared (2012 - $1.60; 2011 - $1.00; 2010 - $0.25)		(13,834)	0
Income recognized for limited partnership unit options		(89)
Limited partnership unit options exercised, value		7
Tax effect of units involved in option exercises and treasury unit transactions		545
Issuance of limited partnership units as compensation		639
Foreign currency translation adjustment, tax	(2,952)
Unrealized loss on cash flow hedging derivatives, tax	(5,825)
Current year activity, net of tax ($210) in 2012, $5,508 in 2011, ($5,825) in 2010 at Dec. 31, 2010	60,048						60,048
Ending balance, value at Dec. 31, 2010	121,628	150,047	(1)	5,290	(33,708)	(4,053)	(29,655)
Current year activity, net of tax ($213) in 2012, $245 in 2011, ($2,952) in 2010) at Dec. 31, 2010	(6,475)					(6,475)
Ending balance, units at Dec. 31, 2010		55,334
Partnership distribution declared, per unit	$ 1,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Limited partnership unit options exercised, units		0
Issuance of limited partnership units as compensation		12
Net income (loss)	65,296	65,295	1
Partnership distribution declared (2012 - $1.60; 2011 - $1.00; 2010 - $0.25)		(55,347)	0
Income recognized for limited partnership unit options		(239)
Limited partnership unit options exercised, value		5
Tax effect of units involved in option exercises and treasury unit transactions		127
Issuance of limited partnership units as compensation		180
Foreign currency translation adjustment, tax	245
Unrealized loss on cash flow hedging derivatives, tax	5,508
Current year activity, net of tax ($210) in 2012, $5,508 in 2011, ($5,825) in 2010 at Dec. 31, 2011	3,767						3,767
Ending balance, value at Dec. 31, 2011	136,350	160,068	0	5,290	(29,008)	(3,120)	(25,888)
Current year activity, net of tax ($213) in 2012, $245 in 2011, ($2,952) in 2010) at Dec. 31, 2011	933					933
Ending balance, units at Dec. 31, 2011		55,346
Partnership distribution declared, per unit	$ 1,600
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Limited partnership unit options exercised, units		16
Issuance of limited partnership units as compensation		256
Net income (loss)	101,857	101,856	1
Partnership distribution declared (2012 - $1.60; 2011 - $1.00; 2010 - $0.25)		(88,813)	0
Income recognized for limited partnership unit options		345
Limited partnership unit options exercised, value		76
Tax effect of units involved in option exercises and treasury unit transactions		1,208
Issuance of limited partnership units as compensation		2,920
Foreign currency translation adjustment, tax	(213)
Unrealized loss on cash flow hedging derivatives, tax	(210)
Current year activity, net of tax ($210) in 2012, $5,508 in 2011, ($5,825) in 2010 at Dec. 31, 2012	139						139
Ending balance, value at Dec. 31, 2012	154,451	177,660	1	5,290	(28,500)	(2,751)	(25,749)
Current year activity, net of tax ($213) in 2012, $245 in 2011, ($2,952) in 2010) at Dec. 31, 2012	$ 369					$ 369
Ending balance, units at Dec. 31, 2012		55,618