Fair Value Measurements (Details) (USD $)
In Millions, unless otherwise specified |
Jun. 30, 2012
Fair Value, Measurements, Recurring [Member]
|
Dec. 31, 2011
Fair Value, Measurements, Recurring [Member]
|
Dec. 31, 2011
Fair Value, Measurements, Nonrecurring [Member]
|
Jun. 30, 2012
Fair Value, Inputs, Level 1 [Member]
Fair Value, Measurements, Recurring [Member]
|
Dec. 31, 2011
Fair Value, Inputs, Level 1 [Member]
Fair Value, Measurements, Recurring [Member]
|
Jun. 30, 2012
Fair Value, Inputs, Level 2 [Member]
Fair Value, Measurements, Recurring [Member]
|
Dec. 31, 2011
Fair Value, Inputs, Level 2 [Member]
Fair Value, Measurements, Recurring [Member]
|
Dec. 31, 2011
Fair Value, Inputs, Level 2 [Member]
Fair Value, Measurements, Nonrecurring [Member]
|
Jul. 02, 2011
Fair Value, Inputs, Level 2 [Member]
Fair Value, Measurements, Nonrecurring [Member]
|
Jun. 30, 2012
Fair Value, Inputs, Level 3 [Member]
Fair Value, Measurements, Recurring [Member]
|
Dec. 31, 2011
Fair Value, Inputs, Level 3 [Member]
Fair Value, Measurements, Recurring [Member]
|
---|---|---|---|---|---|---|---|---|---|---|---|
Assets: | |||||||||||
Cash equivalents | $ 192.2 | $ 135.2 | $ 192.2 | $ 135.2 | $ 0 | $ 0 | $ 0 | $ 0 | |||
Short-term investments in marketable securities | 96.4 | 76.7 | 0.8 | 5.5 | 95.6 | 71.2 | 0 | 0 | |||
Long-term investments in marketable securities | 46.5 | 92.9 | 46.5 | 92.9 | 0 | 0 | 0 | 0 | |||
Restricted cash | 20.0 | 20.0 | 20.0 | 20.0 | 0 | 0 | 0 | 0 | |||
Equity investments | 0.9 | 0.7 | 0.9 | 0.7 | 0 | 0 | 0 | 0 | |||
Derivatives | 2.0 | 3.9 | 0 | 0 | 2.0 | 3.9 | 0 | 0 | |||
Total assets | 358.0 | 329.4 | 260.4 | 254.3 | 97.6 | 75.1 | 0 | 0 | |||
Liabilities: | |||||||||||
Derivatives | 11.3 | 8.0 | 0 | 0 | 11.3 | 8.0 | 0 | 0 | |||
Total liabilities | 11.3 | 8.0 | 0 | 0 | 11.3 | 8.0 | 0 | 0 | |||
Assets Measured at fair value on a non-recurring basis [Abstract] | |||||||||||
Assets measured at fair value on a nonrecurring basis | $ 5.5 | $ 4.7 | $ 0.8 |