Property and Equipment (Notes)

12 Months Ended

Dec. 31, 2013

Property, Plant and Equipment [Abstract]

Property and Equipment

Property and Equipment

Property and equipment consisted of the following as of December 31, 2013 and 2012 (dollars in thousands):

	December 31, 2013			December 31, 2012			Estimated Useful Life in Years
Computer and networking equipment	$	737,957		$	655,043		3-4
Purchased software	40,237			35,176			3
Furniture and fixtures	20,838			16,917			5
Office equipment	10,353			7,109			3
Leasehold improvements	64,471			44,539			2-12
Internal-use software	340,421			272,441			2-3
Property and equipment, gross	1,214,277			1,031,225
Accumulated depreciation and amortization	(763,990		)	(686,134		)
Property and equipment, net	$	450,287		$	345,091

Depreciation and amortization expense on property and equipment and capitalized internal-use software for the years ended December 31, 2013, 2012 and 2011 was $162.9 million, $183.2 million and $150.8 million, respectively. During the years ended December 31, 2013, 2012 and 2011, the Company capitalized $12.3 million, $9.3 million and $7.5 million, respectively, of stock-based compensation related to employees who developed and enhanced internal-use software applications.

During the years ended December 31, 2013 and 2012, the Company wrote off $68.5 million and $77.4 million, respectively, of property and equipment, gross, along with the associated accumulated depreciation and amortization. The write-offs were primarily related to computer and networking equipment and internal-use software no longer in use. These assets were substantially depreciated and amortized.