Software



	As of December 31,
	2013			2012
Software	$	457.7		$	182.8
Accumulated amortization	(114.2		)	(95.6		)
Software, net	$	343.5		$	87.2

During the fourth quarter of 2013, we recorded $257.8 million of software associated with our acquisition of WMS including $201.2 million of intellectual property. In the years ended December 31, 2013 and 2012, we capitalized $37.9 million and $44.0 million, respectively, of software systems development costs. The total amount charged to amortization expense for amortization of software costs was $39.6 million, $28.0 million and $24.0 million for the years ended December 31, 2013, 2012 and 2011, respectively.

During the year ended December 31, 2013, we recorded accelerated amortization expense of $8.0 million related to the write-down of certain development costs including $4.6 million related to software for a line of gaming machines we discontinued as a result of our reorganization plans and $3.4 million related to obsolete software in our gaming business. During 2012, we recorded $3.1 million related to the write-down of certain hardware development costs in our licensed brands business and recorded an impairment of $6.4 million in 2011 as a result of our migration to a new platform technology in our U.K. LBO business.