Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2018

Accounting Policies [Abstract]

Property Plant And Equipment Estimated Useful Life

We compute depreciation of property, plant, and equipment using the straight-line method, based on the estimated useful life of each asset as follows:

Assets	Lives in Years
Refining	8 to 47
Logistics	3 to 30
Retail	3 to 30
Corporate	3 to 7
Software	3

Summary of Depreciation Expense

The following table summarizes depreciation expense excluded from each line item in our consolidated statements of operations (in thousands):

	Year Ended December 31,
	2018		2017		2016
Cost of revenues	$	6,722	$	6,029	$	4,604
Operating expense	28,037		22,861		16,340
General and administrative expense	4,233		2,929		2,108