Condensed Statements of Shareholders' Equity (USD $) In Millions, unless otherwise specified	Total	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Loss	Retained Earnings
Balance at Dec. 31, 2012	$ 998.4	$ 80.2	$ 856.1	$ (371.3)	$ 433.4
Balance (in shares) at Dec. 31, 2012		80.2
Net income	153.9	0	0	0	153.9
Other comprehensive income	8.2	0	0	8.2	0
Dividends paid:
Common stock ($0.60 per share)	(48.1)	0	0	0	(48.1)
Common stock repurchased and retired (in shares)	(1.2)	(1.2)
Common stock repurchased and retired	(28.8)	(1.2)	(27.6)	0	0
Common stock issued for:
Stock options exercised (in shares)	0.4	0.4
Stock options exercised	7.6	0.4	7.2	0	0
Other Transactions (in shares)		0.2
Other Transactions	3.2	0.2	3.0	0	0
Stock-based compensation	2.9	0	2.9	0	0
Balance at Sep. 30, 2013	1,097.3	79.6	841.6	(363.1)	539.2
Balance (in shares) at Sep. 30, 2013		79.6
Balance at Dec. 31, 2013	1,101.1	79.4	838.8	(365.1)	548.0
Balance (in shares) at Dec. 31, 2013		79.4
Net income	92.9	0	0	0	92.9
Other comprehensive income	8.7	0	0	8.7	0
Dividends paid:
Common stock ($0.60 per share)	(47.4)	0	0	0	(47.4)
Common stock repurchased and retired (in shares)	(1.7)	(1.7)
Common stock repurchased and retired	(44.7)	(1.7)	(43.0)	0	0
Common stock issued for:
Stock options exercised (in shares)	0.4	0.4
Stock options exercised	8.6	0.4	8.2	0	0
Other Transactions (in shares)		0.1
Other Transactions	2.0	0.1	1.9	0	0
Balance at Sep. 30, 2014	$ 1,121.2	$ 78.2	$ 805.9	$ (356.4)	$ 593.5
Balance (in shares) at Sep. 30, 2014		78.2