Note 7 - Stock-based Compensation - RSU Summary (Details) - $ / shares		12 Months Ended
		Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Beginning balance (in shares)		4,232,000	4,048,000	3,582,000
Weighted-Average Grant Date Fair Value Per Share (in dollars per share)		$ 32.64	$ 26.14	$ 22.53
Granted (in shares)		1,349,000	1,198,000	1,287,000
Weighted-Average Grant Date Fair Value Per Share (in dollars per share)		$ 43.28	$ 48.11	$ 35.19
Released (in shares)		(975,000)	(948,000)	(772,000)
Weighted-Average Grant Date Fair Value Per Share (in dollars per share)		$ 31.36	$ 24.47	$ 19.48
Forfeited (in shares)		(336,000)	(66,000)	(49,000)
Weighted-Average Grant Date Fair Value Per Share (in dollars per share)		$ 30.38	$ 33.06	$ 19.77
Ending balance (in shares)		4,270,000	4,232,000	4,048,000
Weighted-Average Grant Date Fair Value Per Share (in dollars per share)		$ 36.47	$ 32.64	$ 26.14
Released (in shares)		975,000	948,000	772,000
Forfeited (in shares)		336,000	66,000	49,000
GrantedWeighted-Average Grant Date Fair Value Per Share (in dollars per share)		$ 43.28	$ 48.11	$ 35.19
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period		1,349,000	1,198,000	1,287,000
Time-Based RSUs [Member]
Beginning balance (in shares)		499,000	589,000	754,000
Weighted-Average Grant Date Fair Value Per Share (in dollars per share)		$ 40.75	$ 28.48	$ 19.41
Granted (in shares)		133,000	271,000	335,000
Weighted-Average Grant Date Fair Value Per Share (in dollars per share)		$ 63	$ 49.82	$ 36.71
Released (in shares)		(239,000)	(319,000)	(468,000)
Weighted-Average Grant Date Fair Value Per Share (in dollars per share)		$ 36.43	$ 26.56	$ 20.36
Forfeited (in shares)		(27,000)	(42,000)	(32,000)
Weighted-Average Grant Date Fair Value Per Share (in dollars per share)		$ 45.35	$ 35.60	$ 19.75
Ending balance (in shares)		366,000	499,000	589,000
Weighted-Average Grant Date Fair Value Per Share (in dollars per share)		$ 51.35	$ 40.75	$ 28.48
Released (in shares)		239,000	319,000	468,000
Forfeited (in shares)		27,000	42,000	32,000
GrantedWeighted-Average Grant Date Fair Value Per Share (in dollars per share)		$ 63	$ 49.82	$ 36.71
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period		133,000	271,000	335,000
PSUs and MPSUs [Member]
Beginning balance (in shares)		1,933,000	1,659,000	1,028,000
Weighted-Average Grant Date Fair Value Per Share (in dollars per share)		$ 38.99	$ 28.11	$ 23.02
Granted (in shares)	[1]	1,216,000	927,000	952,000
Weighted-Average Grant Date Fair Value Per Share (in dollars per share)		$ 41.12	$ 47.61	$ 34.65
Released (in shares)		(736,000)	(629,000)	(304,000)
Weighted-Average Grant Date Fair Value Per Share (in dollars per share)		$ 29.71	$ 23.40	$ 18.12
Forfeited (in shares)		(129,000)	(24,000)	(17,000)
Weighted-Average Grant Date Fair Value Per Share (in dollars per share)		$ 36.82	$ 28.68	$ 19.79
Ending balance (in shares)		2,284,000	1,933,000	1,659,000
Weighted-Average Grant Date Fair Value Per Share (in dollars per share)		$ 43.24	$ 38.99	$ 28.11
Released (in shares)		736,000	629,000	304,000
Forfeited (in shares)		129,000	24,000	17,000
GrantedWeighted-Average Grant Date Fair Value Per Share (in dollars per share)		$ 41.12	$ 47.61	$ 34.65
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period	[1]	1,216,000	927,000	952,000
MSUs [Member]
Beginning balance (in shares)		1,800,000	1,800,000	1,800,000
Weighted-Average Grant Date Fair Value Per Share (in dollars per share)		$ 23.57	$ 23.57	$ 23.57
Granted (in shares)
Weighted-Average Grant Date Fair Value Per Share (in dollars per share)
Released (in shares)
Weighted-Average Grant Date Fair Value Per Share (in dollars per share)
Forfeited (in shares)		(180,000)
Weighted-Average Grant Date Fair Value Per Share (in dollars per share)		$ 23.57
Ending balance (in shares)		1,620,000	1,800,000	1,800,000
Weighted-Average Grant Date Fair Value Per Share (in dollars per share)		$ 23.57	$ 23.57	$ 23.57
Released (in shares)
Forfeited (in shares)		180,000
GrantedWeighted-Average Grant Date Fair Value Per Share (in dollars per share)
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period

[1] Amount reflects the number of PSUs and MPSUs that may ultimately be earned based on management’s probability assessment of the performance conditions at each reporting period. In addition, MPSUs are subject to the achievement of market conditions.