Intangible Assets

3 Months Ended

Mar. 31, 2015

Intangible Assets, Net (Excluding Goodwill) [Abstract]

Intangible Assets

Intangible Assets

The following table sets forth the details of the Company's intangible assets at March 31, 2015 and December 31, 2014.

	At March 31, 2015						At December 31, 2014
	Gross		Accumulated Amortization		Net		Gross		Accumulated Amortization		Net
	(in millions)
Directory services agreements	$	666	$	342	$	324	$	666	$	307	$	359
Client relationships	924		693		231		924		649		275
Trademarks and domain names	222		102		120		222		91		131
Patented technologies	42		19		23		42		16		26
Advertising commitment	11		8		3		11		8		3
Total intangible assets	$	1,865	$	1,164	$	701	$	1,865	$	1,071	$	794

Amortization expense for intangible assets was $93 million and $147 million for the three months ended March 31, 2015 and 2014, respectively.

The annual amortization expense for intangible assets is estimated to be $373 million in 2015, $237 million in 2016, $103 million in 2017 and $81 million in 2018.