Stockholders' Equity - Shares Issued under Share Based Compensation (Detail) - shares shares in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options exercised	1,841	15	2,408	140
Total shares	2,045	250	2,835	541
RSUs vested [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
RSUs vested (in shares)	204	235	351	324
Shares purchased pursuant to ESPP [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares purchased pursuant to ESPP	0	0	76	77