Earnings Per Share (Details) - shares shares in Millions	3 Months Ended		12 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Mar. 31, 2016	Mar. 31, 2015
Earnings Per Share [Abstract]
Weighted-average basic common shares outstanding (in shares)	175.8	176.2	175.9	176.0
Potential number of shares issuable under the Company's LTSIP (in shares)	0.3	0.3	0.2	0.3
Weighted-average diluted common shares outstanding (in shares)	176.1	176.5	176.1	176.3