Fair Value Measurements, Available-for-sale Securities (Details) (USD $)
In Millions |
Dec. 31, 2010
|
Dec. 31, 2009
|
---|---|---|
Schedule of Available-for-sale Securities [Line Items] | ||
Market Value | $ 36.6 | $ 36.6 |
Cost Basis | 31.4 | 32.9 |
Gross Unrealized Gains | 5.9 | 4.3 |
Gross Unrealized Losses | 0.7 | 0.6 |
Trading Securities | 4.3 | 1.7 |
Mutual Fund and Unit Trust Investments [Member]
|
||
Schedule of Available-for-sale Securities [Line Items] | ||
Market Value | 32.0 | 31.2 |
Cost Basis | 26.1 | 26.9 |
Gross Unrealized Gains | 5.9 | 4.3 |
Gross Unrealized Losses | 0 | 0 |
Auction Rate Securities [Member]
|
||
Schedule of Available-for-sale Securities [Line Items] | ||
Market Value | 4.6 | 5.4 |
Cost Basis | 5.3 | 6.0 |
Gross Unrealized Gains | 0 | 0 |
Gross Unrealized Losses | $ 0.7 | $ 0.6 |