Intangible Assets

6 Months Ended

Jun. 30, 2013

Intangible Assets, Net (Excluding Goodwill) [Abstract]

Intangible Assets

5. Intangible Assets

The following table summarizes the components of our intangible assets at the dates indicated:

	June 30, 2013						December 31, 2012
	Gross Carrying Amount		Accumulated Amortization		Carrying Value		Gross Carrying Amount		Accumulated Amortization		Carrying Value
Refinery Services:
Customer relationships	$	94,654	$	72,725	$	21,929	$	94,654	$	69,167	$	25,487
Licensing agreements	38,678		24,474		14,204		38,678		22,892		15,786
Supplier relationships	—		—		—		36,469		36,469		—
Segment total	133,332		97,199		36,133		169,801		128,528		41,273
Supply & Logistics:
Customer relationships	35,430		27,485		7,945		35,430		26,403		9,027
Intangibles associated with lease	13,260		2,802		10,458		13,260		2,565		10,695
Trade names	—		—		—		18,888		18,888		—
Segment total	48,690		30,287		18,403		67,578		47,856		19,722
Other	19,890		5,640		14,250		18,932		4,862		14,070
Total	$	201,912	$	133,126	$	68,786	$	256,311	$	181,246	$	75,065

Our amortization expense for the periods presented was as follows:

	Three Months Ended June 30,				Six Months Ended June 30,
	2013		2012		2013		2012
Amortization expense	$	3,609	$	5,355	$	7,236	$	10,870

We estimate that our amortization expense for the next five years will be as follows:

Remainder of	2013	$	7,329
	2014	$	12,440
	2015	$	10,631
	2016	$	9,170
	2017	$	8,007