XML 41 R20.htm IDEA: XBRL DOCUMENT v2.4.1.9
Property, Plant and Equipment (Details) (USD $)
In Thousands, unless otherwise specified
Mar. 31, 2015
Dec. 31, 2014
Property, plant and equipment [Abstract]    
Total property, plant and equipment $ 703,478us-gaap_PropertyPlantAndEquipmentGross $ 693,399us-gaap_PropertyPlantAndEquipmentGross
Less accumulated amortization and depreciation 301,304us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment 287,492us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment
Net property, plant and equipment 402,174us-gaap_PropertyPlantAndEquipmentNet 405,907us-gaap_PropertyPlantAndEquipmentNet
Plant in Service [Member]    
Property, plant and equipment [Abstract]    
Total property, plant and equipment 685,598us-gaap_PropertyPlantAndEquipmentGross
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= us-gaap_OtherPlantInServiceMember		 675,321us-gaap_PropertyPlantAndEquipmentGross
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= us-gaap_OtherPlantInServiceMember
Plant under Construction [Member]    
Property, plant and equipment [Abstract]    
Total property, plant and equipment $ 17,880us-gaap_PropertyPlantAndEquipmentGross
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= us-gaap_AssetUnderConstructionMember		 $ 18,078us-gaap_PropertyPlantAndEquipmentGross
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= us-gaap_AssetUnderConstructionMember