The Company's intangible assets and estimated useful lives are classified as follows:
 
December 31, 2016
 
December 31, 2015
(in thousands)
Gross
Carrying
Amount
 
Accumulated
Amortization
 
Gross
Carrying
Amount
 
Accumulated
Amortization
Finite-lived intangible assets:
 
 
 
 
 
 
 
Developed software and core technologies (3 – 11 years)
$
338,594

 
$
(275,130
)
 
$
336,262

 
$
(251,201
)
Customer lists and contract backlog (5 – 15 years)
159,549

 
(88,414
)
 
159,885

 
(76,160
)
Trade names (2 – 10 years)
127,952

 
(90,289
)
 
127,903

 
(76,493
)
Total
$
626,095

 
$
(453,833
)
 
$
624,050

 
$
(403,854
)
Indefinite-lived intangible assets:
 
 
 
 
 
 
 
Trade names
$
357

 
 
 
$
357