Nature of Operations and Summary of Significant Accounting Policies - Reconciliation of Shares Used in Computation of Basic and Diluted Net Income Per Share (Detail) - shares shares in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basic	79,648	80,449	80,936
Assumed dilution under stock plans	333	442	558
Diluted	79,981	80,891	81,494