Business Acquisitions Contract Price and Fair Value of Consideration Transferred (Details) (USD $) In Thousands, unless otherwise specified	6 Months Ended			0 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014 Alaska Energy Resources Company [Member]	Jul. 01, 2014 Subsequent Event [Member] Alaska Energy Resources Company [Member]	Jul. 01, 2014 Subsequent Event [Member] Alaska Energy Resources Company [Member]
Business Acquisition [Line Items]
Merger Consideration - Total					$ 170,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Cash and Equivalents					19,704
Business Acquisition Recognized Identifiable Assets Acquired and Liabilities Assumed Current and Long-Term Debt					(38,832)
Business Acquisition Contract Price Closing Adjustments					(104)
Business Acquisition Adjusted Contract Price					150,768
Business Combination, Consideration Transferred, Equity Interests Issued and Issuable				150,075
Payments to Acquire Businesses, Gross	4,697	0	4,697
Business Combination, Consideration Transferred				$ 154,772