Note 3 - Stock-based Compensation - RSU Summary (Details)	3 Months Ended
	Mar. 31, 2023 $ / shares shares
Balance (in shares) | shares	2,659,000
Weighted-Average Grant Date Fair Value Per Share, ending balance (in dollars per share) | $ / shares	$ 176.50
Granted (in shares) | shares	273,000
Weighted-Average Grant Date Fair Value Per Share, granted (in dollars per share) | $ / shares	$ 450.13
Vested (in shares) | shares	(295,000)
Weighted-Average Grant Date Fair Value Per Share, vested (in dollars per share) | $ / shares	$ 217.47
Forfeited (in shares) | shares	(9,000)
Weighted-Average Grant Date Fair Value Per Share, forfeited (in dollars per share) | $ / shares	$ 225.18
Balance (in shares) | shares	2,628,000
Weighted-Average Grant Date Fair Value Per Share, ending balance (in dollars per share) | $ / shares	$ 200.37
Time-Based RSUs [Member]
Balance (in shares) | shares	106,000
Weighted-Average Grant Date Fair Value Per Share, ending balance (in dollars per share) | $ / shares	$ 327.13
Granted (in shares) | shares	27,000
Weighted-Average Grant Date Fair Value Per Share, granted (in dollars per share) | $ / shares	$ 467.62
Vested (in shares) | shares	(16,000)
Weighted-Average Grant Date Fair Value Per Share, vested (in dollars per share) | $ / shares	$ 279.89
Forfeited (in shares) | shares	(2,000)
Weighted-Average Grant Date Fair Value Per Share, forfeited (in dollars per share) | $ / shares	$ 361.26
Balance (in shares) | shares	115,000
Weighted-Average Grant Date Fair Value Per Share, ending balance (in dollars per share) | $ / shares	$ 365.93
PSUs and MPSUs [Member]
Balance (in shares) | shares	748,000
Weighted-Average Grant Date Fair Value Per Share, ending balance (in dollars per share) | $ / shares	$ 275.70
Granted (in shares) | shares	246,000	[1]
Weighted-Average Grant Date Fair Value Per Share, granted (in dollars per share) | $ / shares	$ 449.22
Vested (in shares) | shares	(198,000)
Weighted-Average Grant Date Fair Value Per Share, vested (in dollars per share) | $ / shares	$ 291.65
Forfeited (in shares) | shares	(2,000)
Weighted-Average Grant Date Fair Value Per Share, forfeited (in dollars per share) | $ / shares	$ 285.23
Balance (in shares) | shares	794,000
Weighted-Average Grant Date Fair Value Per Share, ending balance (in dollars per share) | $ / shares	$ 326.02
MSUs [Member]
Balance (in shares) | shares	1,805,000
Weighted-Average Grant Date Fair Value Per Share, ending balance (in dollars per share) | $ / shares	$ 126.57
Granted (in shares) | shares	0
Weighted-Average Grant Date Fair Value Per Share, granted (in dollars per share) | $ / shares	$ 0
Vested (in shares) | shares	(81,000)
Weighted-Average Grant Date Fair Value Per Share, vested (in dollars per share) | $ / shares	$ 23.57
Forfeited (in shares) | shares	(5,000)
Weighted-Average Grant Date Fair Value Per Share, forfeited (in dollars per share) | $ / shares	$ 139.15
Balance (in shares) | shares	1,719,000
Weighted-Average Grant Date Fair Value Per Share, ending balance (in dollars per share) | $ / shares	$ 131.39

[1] Amount reflects the number of awards that may ultimately be earned based on management's probability assessment of the achievement of performance conditions at each reporting period.