Intangible Assets (Tables)
 12 Months Ended
Dec. 31, 2014
Finite-Lived Intangible Assets, Net [Abstract]  
Intangible Assets
Our intangible assets include the following:
 
December 31, 2014
 
December 31, 2013
 
Gross Carrying
Value
 
Accumulated
Amortization
 
Net Carrying
Value
 
Gross Carrying
Value
 
Accumulated
Amortization
 
Net Carrying
Value
 
 
 
 
 
(in thousands)
 
 
 
 
 
 
Amortizable intangible assets:
 

 
 

 
 

 
 

 
 

 
 

Licenses
$
1,091,405

 
$
(287,281
)
 
$
804,124

 
$
1,205,450

 
$
(243,081
)
 
$
962,369

Total amortizable intangible assets
$
1,091,405

 
$
(287,281
)
 
$
804,124

 
$
1,205,450

 
$
(243,081
)
 
$
962,369
Estimated Amortization Expense
Based on the carrying amount of intangible assets as of December 31, 2014 and current exchange rates, we estimate amortization expense for each of the next five years to be as follows (in thousands):
Years
Estimated Amortization Expense
2015
$
75,922

2016
75,922

2017
75,922

2018
75,922

2019
75,922