Note 6 - Stockholders' Equity and Equity Compensation (Detail) (USD $) In Millions, except Share data, unless otherwise specified	9 Months Ended	12 Months Ended		24 Months Ended			3 Months Ended		9 Months Ended			3 Months Ended		9 Months Ended		12 Months Ended	9 Months Ended
	Sep. 30, 2012	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2012	Sep. 30, 2012 Employee Plan [Member]	Sep. 30, 2012 Director Plan [Member]	Sep. 30, 2012 Restricted Stock [Member]	Sep. 30, 2011 Restricted Stock [Member]	Sep. 30, 2012 Restricted Stock [Member]	Sep. 30, 2011 Restricted Stock [Member]	Sep. 30, 2012 Deferred Stock Units [Member]	Sep. 30, 2012 Stock Options [Member]	Sep. 30, 2011 Stock Options [Member]	Sep. 30, 2012 Stock Options [Member]	Sep. 30, 2012 In Connection with Equity Compensation Programs [Member]	Dec. 31, 2012 In Connection with Equity Compensation Programs [Member]	Sep. 30, 2012 Through the Open Market Repurchase Program [Member]	Sep. 30, 2012 Minimum [Member]	Sep. 30, 2012 Maximum [Member]
Stock Repurchase Program, Authorized Amount		$ 5.0	$ 5.0	$ 10.0												$ 5.0
Stock Repurchased During Period, Shares (in Shares)															64,122		310,035
Stock Repurchased During Period, Value															1.2		5.0
Treasury Stock Acquired, Average Cost Per Share (in Dollars per share)															$ 18.10		$ 16.13
Stock Issued During Period, Shares, Other (in Shares)	2,769
Stock Options Exchanged for Shares (in Shares)	13,500
Number of Equity-Based Compensation Plans	2
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized (in Shares)					2,500,000	250,000
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant (in Shares)					826,188	208,266
Allocated Share-based Compensation Expense							0.8	1.1	3.0	3.2	0.7	0.5	0.4	1.6
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized							$ 7.2		$ 7.2			$ 2.8		$ 2.8
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized, Period for Recognition									1 year 6 months					1 year 328 days
Deferred Stock Unit, Share Transfer Obligation (in Shares)	1
Stock Options, General Term																		7 years	10 years
Price Per Share For Intrinsic Value Calculation Stock Options (in Dollars per share)												$ 19.16	$ 11.58	$ 19.16