Earnings Per Share (Gains from Premium Put Options) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Other income (expense) | Purchased Put
Derivative Instruments, Gain (Loss) [Line Items]
Gain from sale of put options	$ 3.2	$ 5.0	$ 7.6	$ 8.9