Restructuring And Impairment Costs (Cumulative Restructuring And Impairment Costs) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended				9 Months Ended				12 Months Ended	21 Months Ended
	Dec. 31, 2011		Dec. 31, 2010		Dec. 31, 2011		Dec. 31, 2010		Mar. 31, 2011	Dec. 31, 2011
Restructuring Cost and Reserve [Line Items]
Employee termination benefits										$ 18,278
Pension curtailment and settlement costs									4,100	4,081
Other costs										3,733
Total restructuring cost										26,092
Impairment costs - Property, plant and equipment			5,600							5,632
Total restructuring and impairment costs	399	[1]	10,995	[1]	10,220	[1]	13,964	[1]		31,724
Closure Of Processing Facility In Canada [Member]
Restructuring Cost and Reserve [Line Items]
Employee termination benefits										2,412
Pension curtailment and settlement costs										4,081
Total restructuring cost										6,493
Impairment costs - Property, plant and equipment										5,632
Total restructuring and impairment costs										12,125
Other Restructuring And Cost Reduction Initiatives [Member]
Restructuring Cost and Reserve [Line Items]
Employee termination benefits										15,866
Other costs										3,733
Total restructuring cost										19,599
Total restructuring and impairment costs										$ 19,599

[1] Item is not included in segment operating income, but is included in consolidated operating income.