Condensed Consolidated Statement of Stockholders' Equity (USD $) In Millions, unless otherwise specified	Total	Common Stock	Additional Capital	Accumulated Other Comprehensive Income	Retained Earnings
Balance at Dec. 31, 2012	$ 279.9	$ 31.9	$ 252.7	$ (45.5)	$ 40.8
Balance (in shares) at Dec. 31, 2012		42.6
Increase (Decrease) in Stockholders' Equity
Net Income	46.4				46.4
Other comprehensive income	1.6			1.6
Excess tax benefit and share withholding	1.7		1.7
Share-based compensation	4.3		4.3
Shares issued	1.6	0.2	1.4
Shares issued (in shares)		0.2
Dividends	(19.9)				(19.9)
Balance at Sep. 30, 2013	$ 315.6	$ 32.1	$ 260.1	$ (43.9)	$ 67.3
Balance (in shares) at Sep. 30, 2013		42.8