Quarterly Results - Unaudited - Narrative (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012
Amount of Immaterial Misstatement				$ 1,038
Captive Insurance Equity Affiliate [Member]
Quarterly Charges And Credits, Per Diluted Share	$ 0.08	$ 0.09	$ 0.13	$ 0.11	$ 0.03	$ 0.03	$ 0.04	$ 0.04
Amount of Immaterial Misstatement	$ 0	$ 0	$ 0	$ 1,038
Currency Devaluation [Member]
Quarterly Charges And Credits, Per Diluted Share	$ 0	$ 0	$ 0	$ 0.03
Mineral Oil Excise Tax Refund [Member]
Quarterly Charges And Credits, Per Diluted Share	$ 0	$ 0	$ 0.14	$ 0
Acquisition Related Earnout Adjustment [Member]
Quarterly Charges And Credits, Per Diluted Share	$ 0.06	$ 0	$ 0.03	$ 0	$ 0.09	$ 0	$ 0	$ 0
Cost Streamlining Initiative [Member]
Quarterly Charges And Credits, Per Diluted Share	$ 0.01	$ 0.05	$ 0.02	$ 0
Key Employee Transition Costs [Member]
Quarterly Charges And Credits, Per Diluted Share					$ 0	$ 0	$ 0.03	$ 0
Customer Bankruptcy [Member]
Quarterly Charges And Credits, Per Diluted Share					$ 0	$ 0	$ 0.06	$ 0
Non Income Tax Contingency Charge [Member]
Quarterly Charges And Credits, Per Diluted Share	$ 0.04	$ 0	$ 0	$ 0