Earnings Per Share (Narrative) (Details) - shares shares in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Earnings Per Share [Abstract]
Weighted average shares excluded from denominator for diluted earnings per share because the stock options were anti-dilutive		2.5	0.5	2.3
Restricted stock units issued under stock incentive plan	0.2		0.8	1.0
Restricted stock units excluded from the denominator for diluted earnings per share			0.4	0.5