Note 3 - Stock-based Compensation - RSU Summary (Details) shares in Thousands	6 Months Ended
	Jun. 30, 2022 $ / shares shares
Balance (in shares) | shares	2,509
Weighted-Average Grant Date Fair Value Per Share, beginning balance (in dollars per share) | $ / shares	$ 136.87
Granted (in shares) | shares	602
Weighted-Average Grant Date Fair Value Per Share, granted (in dollars per share) | $ / shares	$ 351.88
Vested (in shares) | shares	(524)
Weighted-Average Grant Date Fair Value Per Share, vested (in dollars per share) | $ / shares	$ 109.63
Forfeited (in shares) | shares	(9)
Weighted-Average Grant Date Fair Value Per Share, forfeited (in dollars per share) | $ / shares	$ 255.02
Balance (in shares) | shares	2,578
Weighted-Average Grant Date Fair Value Per Share, ending balance (in dollars per share) | $ / shares	$ 192.21
Time-Based RSUs [Member]
Balance (in shares) | shares	125
Weighted-Average Grant Date Fair Value Per Share, beginning balance (in dollars per share) | $ / shares	$ 235.82
Granted (in shares) | shares	40
Weighted-Average Grant Date Fair Value Per Share, granted (in dollars per share) | $ / shares	$ 394.57
Vested (in shares) | shares	(43)
Weighted-Average Grant Date Fair Value Per Share, vested (in dollars per share) | $ / shares	$ 183.18
Forfeited (in shares) | shares	(4)
Weighted-Average Grant Date Fair Value Per Share, forfeited (in dollars per share) | $ / shares	$ 297.83
Balance (in shares) | shares	118
Weighted-Average Grant Date Fair Value Per Share, ending balance (in dollars per share) | $ / shares	$ 307.08
PSUs and MPSUs [Member]
Balance (in shares) | shares	1,166
Weighted-Average Grant Date Fair Value Per Share, beginning balance (in dollars per share) | $ / shares	$ 222.78
Granted (in shares) | shares	442	[1]
Weighted-Average Grant Date Fair Value Per Share, granted (in dollars per share) | $ / shares	$ 370.19	[1]
Vested (in shares) | shares	(319)
Weighted-Average Grant Date Fair Value Per Share, vested (in dollars per share) | $ / shares	$ 143.36
Forfeited (in shares) | shares	0
Weighted-Average Grant Date Fair Value Per Share, forfeited (in dollars per share) | $ / shares	$ 0
Balance (in shares) | shares	1,289
Weighted-Average Grant Date Fair Value Per Share, ending balance (in dollars per share) | $ / shares	$ 293.00
MSUs [Member]
Balance (in shares) | shares	1,218
Weighted-Average Grant Date Fair Value Per Share, beginning balance (in dollars per share) | $ / shares	$ 44.59
Granted (in shares) | shares	120
Weighted-Average Grant Date Fair Value Per Share, granted (in dollars per share) | $ / shares	$ 270.15
Vested (in shares) | shares	(162)
Weighted-Average Grant Date Fair Value Per Share, vested (in dollars per share) | $ / shares	$ 23.57
Forfeited (in shares) | shares	(5)
Weighted-Average Grant Date Fair Value Per Share, forfeited (in dollars per share) | $ / shares	$ 207.45
Balance (in shares) | shares	1,171
Weighted-Average Grant Date Fair Value Per Share, ending balance (in dollars per share) | $ / shares	$ 69.93

[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.