Business Acquisitions Business Acquisitions Contract Price and Fair Value of Consideration Transferred (Details) (Alaska Energy Resources Company [Member], USD $) In Thousands, unless otherwise specified	0 Months Ended		12 Months Ended
	Oct. 01, 2014	Jul. 01, 2014	Dec. 31, 2014	Jul. 01, 2014
Alaska Energy Resources Company [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities, Accounts Payable		$ 700		$ 700
Business Acquisition Contract Price		170,000		170,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Cash and Equivalents		19,704		19,704
Business Acquisition Recognized Identifiable Assets Acquired and Liabilities Assumed Current and Long-Term Debt		(38,832)		(38,832)
Business Acquisition Contract Price Closing Adjustments		(58)		(58)
Business Acquisition Adjusted Contract Price		150,814		150,814
Business Combination, Consideration Transferred, Equity Interests Issued and Issuable	44	150,075
Payments to Acquire Businesses, Gross			4,697
Business Combination, Consideration Transferred			154,816
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities, Long-term Debt		3,773		3,773
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities, Other		2,902		2,902
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities		7,375		7,375
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities, Long-term Debt		37,227		37,227
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Capital Lease Obligation		68,840		68,840
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities, Other		15,193		15,193
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities		128,635		128,635
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net		$ 154,816		$ 154,816