Stockholders' Equity and Stock-Based Compensation - Summary of Grant-Date Fair Values of Post-IPO Restricted Stock Granted and Related Assumptions (Parenthetical) (Detail) - U.S. Treasury Securities [Member]	12 Months Ended
	Dec. 31, 2016
Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maturity period of term loan	5 years
Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maturity period of term loan	10 years