Stock Options And Employee Stock Purchase Plan (Stock Options) (Details) - USD ($)	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Number of Shares, Outstanding Beginning of Period	518,341
Number of options granted	0
Number of Shares, Exercised	(41,530)
Number of Shares, Canceled	0
Number of Shares, Outstanding Ending of Period	476,811
Number of Shares, Exercisable	172,211
Number of Shares, Vested and expected to vest	382,175
Weighted-Average Exercise Price, Outstanding Beginning of Period	$ 65.77
Weighted-Average Exercise Price, Granted	0
Weighted-Average Exercise Price, Exercised	22.92
Weighted-Average Exercise Price, Canceled	0
Weighted-Average Exercise Price, Outstanding Ending of Period	69.51
Weighted-Average Exercise Price, Exercisable	59.94
Weighted-Average Exercise Price, Vested and expected to vest	$ 68.14
Weighted-Average Remaining Contractual Term, Outstanding (in years)	6 years 10 months 24 days
Weighted-Average Remaining Contractual Term, Exercisable (in years)	5 years 4 months 24 days
Weighted-Average Remaining Contractual Term, Vested and expected to vest (in years)	6 years 8 months 12 days
Aggregate Intrinsic Value, Outstanding	$ 2,619,831
Aggregate Intrinsic Value, Exercisable	2,585,331
Aggregate Intrinsic Value, Vested and expected to vest	2,619,410
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Total Intrinsic Value	3,000,000.0	$ 8,000,000.0
Share-based Payment Arrangement, Expense	$ 6,313,000	$ 5,086,000
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Estimated Forfeiture Rate	11.57%	12.63%
Share-based Payment Arrangement, Option [Member]
Share-based Payment Arrangement, Expense	$ 200,000	$ 200,000
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition	5 years 8 months 12 days