Share-Based Payments (Details 1) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Summary of share based compensation expense associated with different programs [Abstract]
Subtotal	$ 50.4	$ 43.1	$ 143.6	$ 127.6
Capitalized share-based compensation costs	(3.5)	(2.5)	(9.7)	(7.6)
Share-based compensation expense included in total costs and expenses	46.9	40.6	133.9	120.0
Market stock units
Summary of share based compensation expense associated with different programs [Abstract]
Share-based compensation expense	7.4	4.5	20.6	17.1
Time-vested restricted stock units
Summary of share based compensation expense associated with different programs [Abstract]
Share-based compensation expense	29.9	26.7	96.6	81.2
Cash settled performance shares
Summary of share based compensation expense associated with different programs [Abstract]
Share-based compensation expense	5.8	7.0	9.4	13.0
Performance units
Summary of share based compensation expense associated with different programs [Abstract]
Share-based compensation expense	3.0	3.2	4.2	8.9
Performance stock units settled in stock
Summary of share based compensation expense associated with different programs [Abstract]
Share-based compensation expense	1.3	0.0	3.4	0.0
Performance stock units settled in cash
Summary of share based compensation expense associated with different programs [Abstract]
Share-based compensation expense	1.1	0.0	1.5	0.0
Employee stock purchase plan
Summary of share based compensation expense associated with different programs [Abstract]
Share-based compensation expense	$ 1.9	$ 1.7	$ 7.9	$ 7.4