Consolidated Statement of Comprehensive Income (Parenthetical) (USD $) In Millions	12 Months Ended
Dec. 31, 2010	Dec. 31, 2009	Dec. 31, 2008
Consolidated Statement Of Comprehensive Income Parenthetical [Abstract]
Tax benefit (provision) on unrealized gains and losses on available-for-sale investments included in other comprehensive income	$ (0.5)	$ (0.9)	$ (0.3)
Tax benefit (provision) on unrealized gains on hedging instruments included in other comprehensive income	(0.1)	(0.1)	(0.2)
Tax benefit (provision) on pension and other postretirement benefit liability adjustments in other comprehensive income	$ 9.7	$ (20.9)	$ 63.6

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Tax effect of the gross appreciation or the gross loss, net of reclassification adjustment, in the change in value of available for sale securities during the period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher AICPA
-Name Accounting Research Bulletin (ARB)
-Number 51
-Paragraph 38
-Subparagraph c(3)

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 130
-Paragraph 25

+ Details

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- Definition

Tax effects of the net changes to accumulated comprehensive income during the period related to benefit plans.

+ References

+ Details

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- Definition

Tax effect on reclassification adjustment for accumulated gains and losses from derivative instrument designated and qualifying as the effective portion of cash flow hedges included in accumulated comprehensive income that was realized in net income during the period.

+ References

+ Details

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