Fair Value Measurements (Narrative) (Details) (Fair Value, Measurements, Recurring [Member], Significant Unobservable Inputs (Level 3) [Member])	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2013 Weighted Average [Member] Inventories Component [Member] Assets [Member]	Dec. 31, 2012 Weighted Average [Member] Inventories Component [Member] Assets [Member]	Jun. 30, 2013 Weighted Average [Member] Inventories Component [Member] Liabilities [Member]	Dec. 31, 2012 Weighted Average [Member] Inventories Component [Member] Liabilities [Member]
Fair Value Measurements [Line Items]
Unobservable Price Component, as a percent	10.00%
Threshold of relative value of unobservable inputs to the total fair value for Level 3, as a percent	10.00%
Basis		18.80%	13.50%	34.30%	26.20%