Share-Based Payments (Details 1) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Summary of share based compensation expense associated with different programs [Abstract]
Subtotal	$ 42.8	$ 36.4	$ 93.2	$ 84.5
Capitalized share-based compensation costs	(2.8)	(2.4)	(6.2)	(5.1)
Share-based compensation expense included in total costs and expenses	40.0	34.0	87.0	79.4
Market stock units
Summary of share based compensation expense associated with different programs [Abstract]
Share-based compensation expense	7.1	3.0	13.2	12.6
Time-vested restricted stock units
Summary of share based compensation expense associated with different programs [Abstract]
Share-based compensation expense	30.6	27.6	66.7	54.5
Cash settled performance shares
Summary of share based compensation expense associated with different programs [Abstract]
Share-based compensation expense	(0.7)	2.5	3.6	6.0
Performance units
Summary of share based compensation expense associated with different programs [Abstract]
Share-based compensation expense	2.0	1.2	1.2	5.7
Performance stock units settled in stock
Summary of share based compensation expense associated with different programs [Abstract]
Share-based compensation expense	1.4	0.0	2.1	0.0
Performance stock units settled in cash
Summary of share based compensation expense associated with different programs [Abstract]
Share-based compensation expense	0.3	0.0	0.4	0.0
Employee stock purchase plan
Summary of share based compensation expense associated with different programs [Abstract]
Share-based compensation expense	$ 2.1	$ 2.1	$ 6.0	$ 5.7