Acquisitions Assets Acquired and Liabilities Assumed (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Apr. 01, 2015	Dec. 31, 2014
Business Acquisition [Line Items]
Goodwill	$ 50,101		$ 20,786
Mid Pac Petroleum, LLC [Member]
Business Acquisition [Line Items]
Cash		$ 10,007
Trade accounts receivable		9,914
Inventories		5,398
Prepaid and other current assets		1,449
Property, plant and equipment		39,821
Land		34,800
Goodwill		29,315
Intangible assets		33,647
Other non-current assets		1,228
Accounts payable and other current liabilities		(11,149)
Deferred tax liability		(18,687)
Other non-current liabilities		(7,171)
Total		$ 128,572