Common Stock, Preferred Stock and Equity Plans - Outstanding and Vested Stock Options (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Stock Options
Outstanding at beginning of period (in shares)	6,272,000
Granted (in shares)	22,636	1,520,743	2,297,328
Exercised (in shares)	(1,883,000)
Forfeited (in shares)	(174,000)
Expired (in shares)	0
Outstanding at end of period (in shares)	4,238,000	6,272,000
Stock options exercisable at end of period (in shares)	2,894,000
Weighted-average Exercise Price
Outstanding at beginning of period ( in usd per share)	$ 134.92
Granted ( in usd per share)	286.27
Exercised ( in usd per share)	121.42
Forfeited ( in usd per share)	165.39
Expired ( in usd per share)	0
Outstanding at end of period ( in usd per share)	140.47	$ 134.92
Weighted average exercise price exercisable at the end of the period ( in usd per share)	$ 125.83
Weighted-average Remaining Contractual Life
Outstanding (in years)	6 years 4 months 2 days
Exercisable (in years)	5 years 8 months 23 days
Aggregate Intrinsic Value
Outstanding	$ 397,211
Exercisable	313,936
Total intrinsic value of stock options exercised	255,000	$ 325,900	$ 258,200
Total cash received from employees as a result of employee stock option exercises	$ 228,200	$ 317,800	$ 263,400
Weighted Average
Aggregate Intrinsic Value
Market share price ( in usd per share)	$ 233.91