Summary of Significant Accounting Policies - Weighted Average Shares and Share Equivalents Used to Calculate Basic and Diluted Earnings Per Share (Detail) - shares shares in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Earnings Per Share [Abstract]
Weighted average number of shares outstanding used to calculate basic EPS	3,847	4,022	4,278
Dilutive securities:
Stock options and restricted share units	257	233	157
Weighted average number of shares and share equivalents outstanding used to calculate diluted EPS	4,104	4,255	4,435