Goodwill and Acquired Intangible Assets, Net (Tables)
 3 Months Ended
Mar. 31, 2015
Goodwill and Intangible Assets Disclosure [Abstract]  
Schedule of Intangible Assets and Goodwill [Table Text Block]
A summary of acquired intangible assets and goodwill activity for the three months ended March 31, 2015 is presented below:
(in thousands)
 
Acquired
Intangible
Assets
 
Goodwill
 
Total
Intangible
Assets
Balance as of December 31, 2014
 
$
158,267

 
$
599,863

 
$
758,130

Decreases:
 
 
 
 
 
 
Amortization
 
(6,192
)
 
—

 
(6,192
)
Other (primarily changes in foreign currency exchange rates)
 
(7,805
)
 
(39,116
)
 
(46,921
)
Balance as of March 31, 2015
 
$
144,270

 
$
560,747

 
$
705,017