Note 21 - Incentive Plans - Stock Options Activity (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Options outstanding (in shares)	9,012,441	11,893,761	15,374,145
Options outstanding, weighted average exercise price per share (in dollars per share)	$ 31.09	$ 30.23	$ 28.79
Options outstanding, aggregate intrinsic value	$ 12.1	$ 27.4	$ 29.8	$ 13.1
Options exercised, shares (in shares)	(1,167,819)	(1,019,240)	(1,474,432)
Options exercised, weighted average exercise price per share (in dollars per share)	$ 18.03	$ 18.36	$ 16.19
Options exercised, aggregate intrinsic value	$ 12.4	$ 7.4	$ 9.4
Options forfeited, shares (in shares)	(1,830,893)	(1,862,080)	(2,005,952)
Options forfeited, weighted average exercise price per share (in dollars per share)	$ 39.69	$ 32.55	$ 28.68
Options outstanding (in shares)	6,013,729	9,012,441	11,893,761
Options outstanding, weighted average exercise price per share (in dollars per share)	$ 32.09	$ 31.09	$ 30.23
Options Exercisable, Shares (in shares)	5,144,416	7,617,882	10,159,570
Options exercisable, weighted average exercise price per share (in dollars per share)	$ 32.56	$ 32.90	$ 31.96
Options exercisable, aggregate intrinsic value	$ 11.3	$ 20.0	$ 19.9