Equity (Narrative) (Details) shares in Millions, $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2017 USD ($) shares	Sep. 30, 2017 USD ($)
Equity [Abstract]
Stock Repurchase Program, Authorized Amount	$ 400.0	$ 400.0
Treasury Stock, Shares, Acquired | shares	0.2
Treasury Stock, Value, Acquired, Cost Method		$ 26.9