Earnings Per Share: (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Net Income
Income from continuing operations	$ 19.0	$ 18.4	$ 36.3	$ 39.1
(Loss) income from discontinued operations	0.1	(9.7)	(6.0)	(6.5)
Net Income	$ 19.1	$ 8.7	$ 30.3	$ 32.6
Weighted Average Common Shares
Income From Continuing Operations, Basic (in shares)	42.5	41.7	42.2	41.6
(Loss) income from discontinued operations, Basic (in shares)	42.5	41.7	42.2	41.6
Effect of Dilutive Securities (in shares)	0.3	0.4	0.4	0.4
Income From Continuing Operations, Diluted (in shares)	42.8	42.1	42.6	42.0
(Loss) income from discontinued operations, Diluted (in shares)	42.8	42.1	42.6	42.0
Per Common Share Amount, Basic
Continuing operations (in dollars per share)	$ 0.45	$ 0.44	$ 0.86	$ 0.94
(Loss) income from discontinued operations (in dollars per share)		$ (0.23)	$ (0.14)	$ (0.16)
Net income (in dollars per share)	$ 0.45	$ 0.21	$ 0.72	$ 0.78
Per Common Share Amount, Diluted
Continuing operations (in dollars per share)	$ 0.45	$ 0.44	$ 0.85	$ 0.94
(Loss) income from discontinued operations (in dollars per share)		$ (0.23)	$ (0.14)	$ (0.17)
Net income (in dollars per share)	$ 0.45	$ 0.21	$ 0.71	$ 0.77
Stock options
Earnings Per Share ("EPS")
Antidilutive securities excluded from computation of earnings per share (in shares)	0.5	1.4	0.5	1.2