Earnings Per Share (Details) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Earnings Per Share [Abstract]
Weighted-average basic common shares outstanding (in shares)	175.8	175.5	175.8	175.4	175.7	175.5
Potential number of shares issuable under the Company's LTSIP (in shares)	0.3	0	0.3	0.7	0.3	0.6
Weighted-average diluted common shares outstanding (in shares)	176.1	175.5	176.1	176.1	176.0	176.1