December 31, 

    

December 31, 

    

 Depreciable 

 

 

 

2016

 

2015

 

Lives

 

Land

 

$
5.3

 

$
5.2

 

 

 

 

 

 

Office equipment, machinery and other

 

 
5.6

 

 
5.6

 
3

-
10

years

 

Leasehold improvements

 

 
2.2

 

 

 —

 
7

-
15

years

 

Asset retirement obligation

 

 
27.7

 

 
27.4

 
1

-
43

years

 

Plant in service

 

 
981.1

 

 
975.8

 
1

-
45

years

 

 

 

 
1,021.9

 

 
1,014.0

 

 

 

 

 

 

Less accumulated depreciation

 

 
(288.7)

 

 
(236.3)

 

 

 

 

 

 

Total property, plant and equipment, net

 

$
733.2

 

$
777.7