6. Software and Other Intangible Assets

At June 30, 2013, software net book value totaling $177.8 million, net of $81.6 million of accumulated amortization, includes the net book value of software marketed for external sale of $96.0 million. The remaining software net book value of $81.8 million is comprised of various software that has been acquired or developed for internal use.

Quarterly amortization of software marketed for external sale is computed using the greater of the ratio of current revenues to total estimated revenues expected to be derived from the software or the straight-line method over an estimated useful life of three to ten years. Software for resale amortization expense recorded in the three months ended June 30, 2013 and 2012 totaled $3.5 million and $3.4 million, respectively. Software for resale amortization expense recorded in the six months ended June 30, 2013 and 2012 totaled $6.7 million and $6.2 million, respectively. These software amortization expense amounts are reflected in cost of software license fees in the condensed consolidated statements of operations.

Quarterly amortization of software for internal use is computed using the straight-line method over an estimated useful life of three to ten years. Amortization of software for internal use of $4.4 million and $3.0 million for the three months ended June 30, 2013 and 2012, respectively, is included in depreciation and amortization in the condensed consolidated statements of operations. Amortization of software for internal use was $7.8 million and $5.5 million for the six months ended June 30, 2013 and 2012, respectively.

The carrying amount and accumulated amortization of the Company’s other intangible assets that were subject to amortization at each balance sheet date are as follows (in thousands):


	June 30, 2013							December 31, 2012
	Gross Carrying Amount		Accumulated Amortization			Net Balance		Gross Carrying Amount		Accumulated Amortization			Net Balance
Customer relationships	$	228,183	$	(40,324	)	$	187,859	$	157,364	$	(33,727	)	$	123,637
Purchased contracts		10,729		(10,691	)		38		10,823		(10,549	)		274
Trademarks and tradenames		8,820		(3,098	)		5,722		5,830		(2,096	)		3,734
Covenant not to compete		441		(246	)		195		442		(187	)		255

	$	248,173	$	(54,359	)	$	193,814	$	174,459	$	(46,559	)	$	127,900

Other intangible assets amortization expense for the three months ended June 30, 2013 and 2012 totaled $4.8 million and $3.2 million, respectively. Other intangible assets amortization expense for the six months ended June 30, 2013 and 2012 totaled $8.6 million and $5.5 million, respectively.

Based on capitalized software and other intangible assets at June 30, 2013, estimated amortization expense for future fiscal years is as follows (in thousands):


Fiscal Year Ending December 31,	Software Amortization		Other Intangible Assets Amortization
Remainder of 2013	$	15,938	$	9,489
2014		30,073		17,489
2015		25,515		14,173
2016		21,202		13,194
2017		17,929		12,530
2018		17,216		12,014
Thereafter		49,963		114,925

Total	$	177,836	$	193,814