Equity (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Equity [Abstract]
Net income	$ 100.0	$ 96.9	$ 338.2	$ 268.6
Weighted average common shares outstanding	39.5	42.9	40.7	43.6
Incremental shares from restricted stock units, stock options and convertible debentures	0.3	0.6	0.5	0.9
Weighted average diluted shares outstanding	39.8	43.5	41.2	44.5
Basic earnings per share	$ 2.53	$ 2.26	$ 8.30	$ 6.16
Diluted earnings per share	$ 2.51	$ 2.23	$ 8.22	$ 6.03
Shares outstanding	38.7	42.5	38.7	42.5
Anti-dilutive securities excluded from diluted earnings per share (in shares)	0	0	0	0