Share-Based Payments (Details 1) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Summary of share based compensation expense associated with different programs
Subtotal	$ 48.5	$ 39.2
Capitalized share-based compensation costs	(1.2)	(1.0)
Share-based compensation expense included in total costs and expenses	47.3	38.2
Stock Options [Member]
Summary of share based compensation expense associated with different programs
Share-based compensation expense	0.1	1.1
Market stock units [Member]
Summary of share based compensation expense associated with different programs
Share-based compensation expense	6.0	3.5
Time-vested restricted stock units [Member]
Summary of share based compensation expense associated with different programs
Share-based compensation expense	25.8	27.9
Performance-vested restricted stock units settled in shares [Member]
Summary of share based compensation expense associated with different programs
Share-based compensation expense	0.1	0.4
Cash settled performance shares [Member]
Summary of share based compensation expense associated with different programs
Share-based compensation expense	14.8	4.8
Employee stock purchase plan [Member]
Summary of share based compensation expense associated with different programs
Share-based compensation expense	$ 1.7	$ 1.5