Financial Instruments (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Marketable Debt and Equity Securities
Fair Value	$ 2,895.6	$ 2,592.9
Gross Unrealized Gains	6.6	3.2
Gross Unrealized Losses	(1.4)	(3.1)
Amortized Cost	2,890.4	2,592.8
Corporate debt securities Current [Member]
Marketable Debt and Equity Securities
Fair Value	302.8	155.0
Gross Unrealized Gains	0.4	0.2
Gross Unrealized Losses	(0.1)	(0.1)
Amortized Cost	302.5	154.9
Corporate debt securities Non-current [Member]
Marketable Debt and Equity Securities
Fair Value	611.9	447.6
Gross Unrealized Gains	3.3	1.2
Gross Unrealized Losses	(0.2)	(1.5)
Amortized Cost	608.8	447.9
Government securities Current [Member]
Marketable Debt and Equity Securities
Fair Value	845.6	1,021.0
Gross Unrealized Gains	0.4	0.4
Gross Unrealized Losses	0	0
Amortized Cost	845.2	1,020.6
Government securities Non-current [Member]
Marketable Debt and Equity Securities
Fair Value	694.3	695.5
Gross Unrealized Gains	0.9	0.9
Gross Unrealized Losses	0	(0.2)
Amortized Cost	693.4	694.8
Mortgage and other asset backed securities Current [Member]
Marketable Debt and Equity Securities
Fair Value	5.7	0.1
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Amortized Cost	5.7	0.1
Mortgage and other asset backed securities Non-current [Member]
Marketable Debt and Equity Securities
Fair Value	435.3	273.7
Gross Unrealized Gains	1.6	0.5
Gross Unrealized Losses	(1.1)	(1.3)
Amortized Cost	434.8	274.5
Marketable equity securities [Member]
Marketable Debt and Equity Securities
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	(0.1)
Amortized Cost	1.2	0.2
Fair Value	$ 1.2	$ 0.1

This item represents the cost of debt and equity securities, which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any.

+ References+ Details

Equity securities categorized neither as held-to-maturity nor trading which are intended be sold more than one year from the balance sheet date or operating cycle, if longer.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 115

-Paragraph 3

-Subparagraph c

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 115

-Paragraph 12

-Subparagraph b

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 115

-Paragraph 16

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 25

-Paragraph 1

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=7534914&loc=d3e22054-111558

Reference 5: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Emerging Issues Task Force (EITF)

-Number 86-40

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 6: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 45

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6871852&loc=d3e26626-111562

Reference 7: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 133

-Paragraph 22

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 8: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 115

-Paragraph 13, 17

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

- Definition

This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. This item represents Available-for-sale Securities which consist of all investments in certain debt and equity securities neither classified as trading or held-to-maturity securities. A debt security represents a creditor relationship with an enterprise. Debt securities include, among other items, US Treasury securities, US government securities, municipal securities, corporate bonds, convertible debt, commercial paper, and all securitized debt instruments. An equity security represents an ownership interest in an enterprise or the right to acquire or dispose of an ownership interest in an enterprise at fixed or determinable prices. Equity securities include, among other things, common stock, certain preferred stock, warrant rights, call options, and put options, but do not include convertible debt. An entity may opt to provide the reader with additional narrative text to better understand the nature of investments in debt and equity securities which are categorized as Available-for-sale.

+ References+ Details

- Definition

This item represents the gross unrealized gains for securities, at a point in time, which are categorized neither as held-to-maturity nor trading securities.

+ References+ Details