Note 7 - Stock-based Compensation (Tables)

12 Months Ended

Dec. 31, 2014

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Schedule of Compensation Cost for Share-based Payment Arrangements, Allocation of Share-based Compensation Costs by Plan [Table Text Block]

In millions	2014		2013		2012
Compensation costs (1)	$	24	$	22	$	9
Income tax benefits (1)		1		1		1
Excess tax benefits (2)		-		-		1

Schedule of Share-based Compensation, Stock Options, Activity [Table Text Block]

	Number of options			Weighted average exercise price		Weighted average remaining life (in years)		Aggregate intrinsic value (in millions)
Outstanding - December 31, 2011		1,823,154		$	35.61
Granted		-			-
Exercised		(234,844	)		32.07
Forfeited		(59,720	)		37.34
Outstanding - December 31, 2012(1)		1,528,590		$	36.09
Granted		-			-
Exercised		(617,358	)		35.37
Forfeited		(12,500	)		38.36
Outstanding - December 31, 2013 (1)		898,732		$	36.55		3.0	$	10
Granted		-			-		-
Exercised		(267,182	)		36.84		1.7
Forfeited		(4,000	)		39.71		2.7
Outstanding - December 31, 2014 (1) (2)		627,550		$	36.41		2.2	$	11

Schedule of Nonvested Performance-based Units Activity [Table Text Block]

In millions	Measurement period end date	Fair value accrued at December 31, 2014		Maximum aggregate payout
Granted in 2012	December 31, 2014 (1)	$	8	$	20
Granted in 2013	December 31, 2015		7		21
Granted in 2014	December 31, 2016		4		24

Schedule of Share-based Compensation, Restricted Stock and Restricted Stock Units Activity [Table Text Block]

	Shares of restricted stock			Weighted average remaining vesting period (in years)		Weighted average fair value
Outstanding - December 31, 2011 (1)		477,354				$	34.40
Issued		268,840					40.08
Forfeited		(28,829	)				39.07
Vested		(214,274	)				36.45
Outstanding - December 31, 2012 (1)		503,091				$	39.44
Issued		175,935					42.41
Forfeited		(33,352	)				40.64
Vested		(204,421	)				38.71
Outstanding - December 31, 2013 (1)		441,253			1.8	$	40.82
Issued		262,235			4.4		47.03
Forfeited		(14,895	)		2.4		43.41
Vested		(225,683	)		-		42.31
Outstanding - December 31, 2014 (1)		462,910			1.8	$	43.54

Schedule of Share-based Compensation, Employee Stock Purchase Plan, Activity [Table Text Block]

	2014		2013		2012
Shares purchased on the open market		100,199		97,734		103,589
Average per-share purchase price	$	51.60	$	42.96	$	38.96
Total purchase price discount	$	739,598	$	628,358	$	591,855