Note 6 - Share-based Compensation - Stock Options (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Options outstanding, beginning of period (in shares)	2	98
Options outstanding, beginning of period, weighted average exercise price (in dollars per share)	$ 20.76	$ 20.40
Options outstanding, weighted average remaining contractual term (Year)		18 days	313 days
Options outstanding, aggregate intrinsic value		$ 0.1	$ 6.3
Options exercised (in shares)	(2)	(95)
Options exercised, weighted average exercise price (in dollars per share)	$ 20.76	$ 20.35
Options exercised, aggregate intrinsic value		$ 5.8
Options forfeited (in shares)		(1)
Options forfeited, weighted average exercise price (in dollars per share)		$ 24.27
Options outstanding, end of period (in shares)		2	98
Options outstanding, end of period, weighted average exercise price (in dollars per share)		$ 20.76	$ 20.40