The changes in the net carrying amount of goodwill by reportable segment for the years ended December 31, 2016 and 2015, respectively, are as follows (in millions):
 
Risk
Solutions
 
HR
Solutions
 
Total
Balance as of January 1, 2015
$
5,911

 
$
2,949

 
$
8,860

Goodwill related to current year acquisitions
2

 
16

 
18

Goodwill related to disposals
(1
)
 
(76
)
 
(77
)
Goodwill related to prior year acquisitions
—

 
—

 
—

Foreign currency translation
(319
)
 
(34
)
 
(353
)
Balance as of December 31, 2015
$
5,593

 
$
2,855

 
$
8,448

Goodwill related to current year acquisitions
632

 
10

 
642

Goodwill related to disposals
(8
)
 
(26
)
 
(34
)
Goodwill related to prior year acquisitions
4

 
—

 
4

Foreign currency translation
(268
)
 
(45
)
 
(313
)
Balance as of December 31, 2016
$
5,953

 
$
2,794

 
$
8,747