Stockholders' Equity and Stock-Based Compensation - Summary of Activity Related to Employee Stock Purchase Plan (Detail) - ESPP [Member] - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares Issued	116	148	94
Weighted- Average Purchase Price	$ 123.69	$ 80.21	$ 38.83
Total Cash Proceeds	$ 14,383	$ 11,863	$ 3,635