Property, Plant and Equipment - Summary of Net Property, Plant and Equipment (Details) - Dec. 31, 2014 - Distribution Systems - USD ($)
$ in Millions |
Total |
| Property Plant And Equipment [Line Items] |
|
| Property, plant and equipment, gross |
$ 5,956.7
|
| Less accumulated depreciation |
(3,384.9)
|
| Net property, plant and equipment |
2,571.8
|
| Land |
|
| Property Plant And Equipment [Line Items] |
|
| Property, plant and equipment, gross |
33.0
|
| Building and Improvements |
|
| Property Plant And Equipment [Line Items] |
|
| Property, plant and equipment, gross |
305.5
|
| Poles |
|
| Property Plant And Equipment [Line Items] |
|
| Property, plant and equipment, gross |
223.0
|
| Fiber |
|
| Property Plant And Equipment [Line Items] |
|
| Property, plant and equipment, gross |
1,841.2
|
| Copper |
|
| Property Plant And Equipment [Line Items] |
|
| Property, plant and equipment, gross |
3,430.8
|
| Conduit |
|
| Property Plant And Equipment [Line Items] |
|
| Property, plant and equipment, gross |
89.2
|
| Construction in progress |
|
| Property Plant And Equipment [Line Items] |
|
| Property, plant and equipment, gross |
$ 34.0
|
| Minimum | Building and Improvements |
|
| Property Plant And Equipment [Line Items] |
|
| Depreciable Lives |
3 years
|
| Minimum | Poles |
|
| Property Plant And Equipment [Line Items] |
|
| Depreciable Lives |
13 years
|
| Minimum | Fiber |
|
| Property Plant And Equipment [Line Items] |
|
| Depreciable Lives |
7 years
|
| Minimum | Copper |
|
| Property Plant And Equipment [Line Items] |
|
| Depreciable Lives |
7 years
|
| Minimum | Conduit |
|
| Property Plant And Equipment [Line Items] |
|
| Depreciable Lives |
13 years
|
| Maximum | Building and Improvements |
|
| Property Plant And Equipment [Line Items] |
|
| Depreciable Lives |
40 years
|
| Maximum | Poles |
|
| Property Plant And Equipment [Line Items] |
|
| Depreciable Lives |
40 years
|
| Maximum | Fiber |
|
| Property Plant And Equipment [Line Items] |
|
| Depreciable Lives |
40 years
|
| Maximum | Copper |
|
| Property Plant And Equipment [Line Items] |
|
| Depreciable Lives |
40 years
|
| Maximum | Conduit |
|
| Property Plant And Equipment [Line Items] |
|
| Depreciable Lives |
47 years
|