Note 6 - Stockholders' Equity (Detail) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended	20 Months Ended
	Mar. 31, 2013	Mar. 31, 2013	Jul. 31, 2012	Aug. 31, 2011
Treasury Stock Acquired, Average Cost Per Share (in Dollars per share)	$ 45.04
Stock Repurchased During Period, Value (in Dollars)	$ 2.7
Shares Paid for Tax Withholding for Share Based Compensation	59,721
Common Class A [Member]
Stock Repurchase Program, Number of Shares Authorized to be Repurchased			1,000,000	2,000,000
Stock Repurchased During Period, Shares	127,900	1,273,047
Treasury Stock Acquired, Average Cost Per Share (in Dollars per share)	$ 40.76
Stock Repurchased During Period, Value (in Dollars)	$ 5.2
Stock Repurchase Program, Remaining Number of Shares Authorized to be Repurchased	1,726,953	1,726,953