Stockholders' Equity - Stock Option Plan Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Shares [Rollforward]
Balance at beginning of period (shares)	1,736,304
Granted (shares)	338,617
Exercised (shares)	(112,011)
Forfeited (shares)	(6,531)
Balance at end of period (shares)	1,956,379	1,736,304
Exercisable at end of period (shares)	1,454,726
Options vested and expected to vest at end of period (shares)	1,956,379
Weighted Average Exercise Price [Roll Forward]
Balance at beginning of period (USD per share)	$ 66.71
Granted (USD per share)	116.69
Exercised (USD per share)	23.65
Forfeited (USD per share)	139.37
Balance at end of period (USD per share)	77.54	$ 66.71
Exercisable at end of period (USD per share)	61.82
Options vested and expected to vest at end of period (USD per share)	$ 77.54
Weighted Average Remaining Contractual Term in Years	5 years 5 months 12 days	5 years 5 months 19 days
Exercisable, Weighted Average Remaining Contractual Term in Years	4 years 5 months 1 day
Options vested and expected to vest, Weighted Average Remaining Contractual Term in Years	5 years 5 months 12 days
Aggregate Intrinsic Value	$ 72,002	$ 125,858
Exercisable, Aggregate Intrinsic Value	70,345
Options vested and expected to vest, Aggregate Intrinsic Value	$ 72,002