CASH, CASH EQUIVALENTS AND MARKETABLE SECURITIES (DETAILS) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	Dec. 31, 2011	Dec. 31, 2010
Cash and Cash Equivalents [Abstract]
Cash	$ 11.3		$ 11.3		$ 62.1
Money market funds and other securities	16.2		16.2		40.1
Cash and cash equivalents	27.5	67.5	27.5	67.5	102.2	89.5
Available-for-sale Securities, Current [Abstract]
Marketable securities, Cost Basis	1,143.3		1,143.3		1,029.5
Marketable securities, Unrealized Gains	15.0		15.0		12.2
Marketable securities, Unrealized Losses	(0.2)		(0.2)		(3.0)
Marketable securities, Fair Value	1,158.1		1,158.1		1,038.7
Cash and marketables securities, Cost Basis	1,170.8		1,170.8		1,131.7
Total cash and marketable securities	1,185.6		1,185.6		1,140.9
Available-for-sale Securities, Activity [Abstract]
Proceeds from sales and maturities	271.1	238.2	701.5	697.2
Gross realized gains	2.2	2.9	5.8	6.2
Gross realized losses	0.4	0.3	1.2	2.0
Other-than-temporary impairments on investments	0	1.5	0.3	1.5
Percentage of marketable securities maturing in 2012	3.70%		3.70%
Percentage of marketable securities maturing in 2013	27.10%		27.10%
Percentage of marketable securities maturing after 2013	69.20%		69.20%
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Investments with continuous unrealized losses, Less than 12 months, Fair Value	47.5		47.5		204.2
Investments with continuous unrealized losses, Less than 12 months, Unrealized Losses	(0.1)		(0.1)		(2.7)
Investments with continuous unrealized losses, Greater than 12 months, Fair Value	5.6		5.6		4.0
Investments with continuous unrealized losses, Greater than 12 months, Unrealized Losses	(0.1)		(0.1)		(0.3)
Investments with continuous unrealized losses, Total Fair Value	53.1		53.1		208.2
Investments with continuous unrealized losses, Total Unrealized Losses	(0.2)		(0.2)		(3.0)
U.S. government and agency securities [Member]
Available-for-sale Securities, Current [Abstract]
Marketable securities, Cost Basis	329.5		329.5		292.5
Marketable securities, Unrealized Gains	2.5		2.5		3.4
Marketable securities, Unrealized Losses	0		0		0
Marketable securities, Fair Value	332.0		332.0		295.9
Foreign government bonds [Member]
Available-for-sale Securities, Current [Abstract]
Marketable securities, Cost Basis	44.5		44.5		24.9
Marketable securities, Unrealized Gains	1.0		1.0		0.5
Marketable securities, Unrealized Losses	0		0		0
Marketable securities, Fair Value	45.5		45.5		25.4
Asset-backed securities [Member]
Available-for-sale Securities, Current [Abstract]
Marketable securities, Cost Basis	101.4		101.4		58.2
Marketable securities, Unrealized Gains	0.6		0.6		0.1
Marketable securities, Unrealized Losses	0		0		(0.3)
Marketable securities, Fair Value	102.0		102.0		58.0
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Investments with continuous unrealized losses, Less than 12 months, Fair Value					31.7
Investments with continuous unrealized losses, Less than 12 months, Unrealized Losses					(0.1)
Investments with continuous unrealized losses, Greater than 12 months, Fair Value					1.1
Investments with continuous unrealized losses, Greater than 12 months, Unrealized Losses					(0.2)
Investments with continuous unrealized losses, Total Fair Value					32.8
Investments with continuous unrealized losses, Total Unrealized Losses					(0.3)
Mortgage-backed securities [Member]
Available-for-sale Securities, Current [Abstract]
Marketable securities, Cost Basis	118.2		118.2		124.1
Marketable securities, Unrealized Gains	1.2		1.2		1.1
Marketable securities, Unrealized Losses	(0.1)		(0.1)		(0.3)
Marketable securities, Fair Value	119.3		119.3		124.9
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Investments with continuous unrealized losses, Less than 12 months, Fair Value	32.7		32.7		35.1
Investments with continuous unrealized losses, Less than 12 months, Unrealized Losses	(0.1)		(0.1)		(0.2)
Investments with continuous unrealized losses, Greater than 12 months, Fair Value	4.3		4.3		1.9
Investments with continuous unrealized losses, Greater than 12 months, Unrealized Losses	0		0		(0.1)
Investments with continuous unrealized losses, Total Fair Value	37.0		37.0		37.0
Investments with continuous unrealized losses, Total Unrealized Losses	(0.1)		(0.1)		(0.3)
Corporate notes and bonds [Member]
Available-for-sale Securities, Current [Abstract]
Marketable securities, Cost Basis	530.4		530.4		518.0
Marketable securities, Unrealized Gains	9.6		9.6		7.0
Marketable securities, Unrealized Losses	(0.1)		(0.1)		(2.4)
Marketable securities, Fair Value	539.9		539.9		522.6
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Investments with continuous unrealized losses, Less than 12 months, Fair Value	14.8		14.8		137.4
Investments with continuous unrealized losses, Less than 12 months, Unrealized Losses	0		0		(2.4)
Investments with continuous unrealized losses, Greater than 12 months, Fair Value	1.3		1.3		1.0
Investments with continuous unrealized losses, Greater than 12 months, Unrealized Losses	(0.1)		(0.1)		0
Investments with continuous unrealized losses, Total Fair Value	16.1		16.1		138.4
Investments with continuous unrealized losses, Total Unrealized Losses	(0.1)		(0.1)		(2.4)
Municipal securities [Member]
Available-for-sale Securities, Current [Abstract]
Marketable securities, Cost Basis	19.3		19.3		11.8
Marketable securities, Unrealized Gains	0.1		0.1		0.1
Marketable securities, Unrealized Losses	0		0		0
Marketable securities, Fair Value	$ 19.4		$ 19.4		$ 11.9