CASH, CASH EQUIVALENTS AND MARKETABLE SECURITIES (DETAILS) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009	Dec. 31, 2008
Cash and Cash Equivalents [Abstract]
Cash	$ 62.1	$ 6.6
Money market funds	40.1	82.9
Cash and cash equivalents	102.2	89.5	164.2	283.1
Available-for-sale Securities, Current [Abstract]
Marketable securities, Cost Basis	1,029.5	1,105.8
Marketable securities, Unrealized Gains	12.2	16.3
Marketable securities, Unrealized Losses	(3.0)	(3.4)
Marketable securities, Fair Value	1,038.7	1,118.7
Cash and marketables securities, Cost Basis	1,131.7	1,195.3
Total cash and marketable securities	1,140.9	1,208.2
Available-for-sale Securities, Activity [Abstract]
Proceeds from sales and maturities	955.7	931.0	725.0
Gross realized gains	7.5	10.4	7.0
Gross realized losses	2.3	2.3	2.3
Other-then-temporarily impairments on investments	2.2	0	2.2
Percentage of marketable securities maturing in 2012	23.40%
Percentage of marketable securities maturing in 2013	35.80%
Percentage of marketable securities maturing after 2013	40.80%
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Investments with continuous unrealized losses, Less than 12 months, Fair Value	204.2	290.9
Investments with continuous unrealized losses, Less than 12 months, Unrealized Losses	(2.7)	(2.2)
Investments with continuous unrealized losses, Greater than 12 months, Fair Value	4.0	54.1
Investments with continuous unrealized losses, Greater than 12 months, Unrealized Losses	(0.3)	(1.2)
Investments with continuous unrealized losses, Total Fair Value	208.2	345.0
Investments with continuous unrealized losses, Total Unrealized Losses	(3.0)	(3.4)
U.S. government securities [Member]
Available-for-sale Securities, Current [Abstract]
Marketable securities, Cost Basis	292.5	469.8
Marketable securities, Unrealized Gains	3.4	4.3
Marketable securities, Unrealized Losses	0	(1.2)
Marketable securities, Fair Value	295.9	472.9
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Investments with continuous unrealized losses, Less than 12 months, Fair Value		163.3
Investments with continuous unrealized losses, Less than 12 months, Unrealized Losses		(1.2)
Investments with continuous unrealized losses, Greater than 12 months, Fair Value		0
Investments with continuous unrealized losses, Greater than 12 months, Unrealized Losses		0
Investments with continuous unrealized losses, Total Fair Value		163.3
Investments with continuous unrealized losses, Total Unrealized Losses		(1.2)
Foreign government bonds [Member]
Available-for-sale Securities, Current [Abstract]
Marketable securities, Cost Basis	24.9	41.0
Marketable securities, Unrealized Gains	0.5	0.8
Marketable securities, Unrealized Losses	0	(0.2)
Marketable securities, Fair Value	25.4	41.6
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Investments with continuous unrealized losses, Less than 12 months, Fair Value		0
Investments with continuous unrealized losses, Less than 12 months, Unrealized Losses		0
Investments with continuous unrealized losses, Greater than 12 months, Fair Value		41.6
Investments with continuous unrealized losses, Greater than 12 months, Unrealized Losses		(0.2)
Investments with continuous unrealized losses, Total Fair Value		41.6
Investments with continuous unrealized losses, Total Unrealized Losses		(0.2)
Asset-backed securities [Member]
Available-for-sale Securities, Current [Abstract]
Marketable securities, Cost Basis	58.2	51.7
Marketable securities, Unrealized Gains	0.1	0.3
Marketable securities, Unrealized Losses	(0.3)	(0.3)
Marketable securities, Fair Value	58.0	51.7
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Investments with continuous unrealized losses, Less than 12 months, Fair Value	31.7	15.6
Investments with continuous unrealized losses, Less than 12 months, Unrealized Losses	(0.1)	(0.1)
Investments with continuous unrealized losses, Greater than 12 months, Fair Value	1.1	1.9
Investments with continuous unrealized losses, Greater than 12 months, Unrealized Losses	(0.2)	(0.2)
Investments with continuous unrealized losses, Total Fair Value	32.8	17.5
Investments with continuous unrealized losses, Total Unrealized Losses	(0.3)	(0.3)
Mortgage-backed securities [Member]
Available-for-sale Securities, Current [Abstract]
Marketable securities, Cost Basis	124.1	125.7
Marketable securities, Unrealized Gains	1.1	1.0
Marketable securities, Unrealized Losses	(0.3)	(1.2)
Marketable securities, Fair Value	124.9	125.5
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Investments with continuous unrealized losses, Less than 12 months, Fair Value	35.1	51.4
Investments with continuous unrealized losses, Less than 12 months, Unrealized Losses	(0.2)	(0.4)
Investments with continuous unrealized losses, Greater than 12 months, Fair Value	1.9	8.8
Investments with continuous unrealized losses, Greater than 12 months, Unrealized Losses	(0.1)	(0.8)
Investments with continuous unrealized losses, Total Fair Value	37.0	60.2
Investments with continuous unrealized losses, Total Unrealized Losses	(0.3)	(1.2)
Corporate notes and bonds [Member]
Available-for-sale Securities, Current [Abstract]
Marketable securities, Cost Basis	518.0	411.1
Marketable securities, Unrealized Gains	7.0	9.7
Marketable securities, Unrealized Losses	(2.4)	(0.5)
Marketable securities, Fair Value	522.6	420.3
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Investments with continuous unrealized losses, Less than 12 months, Fair Value	137.4	60.6
Investments with continuous unrealized losses, Less than 12 months, Unrealized Losses	(2.4)	(0.5)
Investments with continuous unrealized losses, Greater than 12 months, Fair Value	1.0	1.8
Investments with continuous unrealized losses, Greater than 12 months, Unrealized Losses	0	0
Investments with continuous unrealized losses, Total Fair Value	138.4	62.4
Investments with continuous unrealized losses, Total Unrealized Losses	(2.4)	(0.5)
Municipal securities [Member]
Available-for-sale Securities, Current [Abstract]
Marketable securities, Cost Basis	11.8	6.5
Marketable securities, Unrealized Gains	0.1	0.2
Marketable securities, Unrealized Losses	0	0
Marketable securities, Fair Value	$ 11.9	$ 6.7