|
Condensed Consolidated Balance Sheets (Unaudited) (Parentheticals) (USD $)
In Millions, except Share data, unless otherwise specified
|
Mar. 31, 2015
|
Dec. 31, 2014
|
| Statement Of Financial Position Parenthetical [Line Items] |
|
|
| Accumulated depreciation |
$ 4,680.0 |
$ 4,633.4 |
| Preferred stock, par value |
$ 0.01 |
$ 0.01 |
| Preferred stock, authorized |
15,000,000 |
15,000,000 |
| Preferred stock, issued |
0 |
0 |
| Preferred stock, outstanding |
0 |
0 |
| Class A Common Stock [Member] |
|
|
| Statement Of Financial Position Parenthetical [Line Items] |
|
|
| Common stock, par value |
$ 0.01 |
$ 0.01 |
| Common stock, authorized |
194,203,987 |
194,203,987 |
| Common stock, issued |
17,176,046 |
17,176,046 |
| Common stock, outstanding |
17,176,046 |
17,176,046 |
| Class B Common Stock [Member] |
|
|
| Statement Of Financial Position Parenthetical [Line Items] |
|
|
| Common stock, par value |
$ 0.01 |
$ 0.01 |
| Common stock, authorized |
87,008,602 |
87,008,602 |
| Common stock, issued |
0 |
0 |
| Common stock, outstanding |
0 |
0 |
| No Class Common Stock [Member] |
|
|
| Statement Of Financial Position Parenthetical [Line Items] |
|
|
| Common stock, par value |
$ 0.01 |
$ 0.01 |
| Common stock, authorized |
1,000,000,000 |
1,000,000,000 |
| Common stock, issued |
370,124,178 |
369,987,783 |
| Common stock, outstanding |
347,940,354 |
350,364,236 |