Number of Unvested Restricted Stock Unit Awards Outstanding (Detail) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 30, 2018 USD ($) $ / shares shares	[1]
Share-Based Compensation Arrangement By Share-Based Payment Award [Line Items]
Number of shares outstanding, Awards balance | shares	592,592
Number of shares outstanding, Awards granted | shares	198,846
Number of shares outstanding, Awards vested | shares	(267,760)
Number of shares outstanding, Awards forfeited | shares	0
Number of shares outstanding, Awards balance | shares	523,678
Weighted-average grant date fair value, Awards balance | $ / shares	$ 45.91
Weighted-average grant date fair value, Awards granted | $ / shares	80.14
Weighted-average grant date fair value, Awards vested | $ / shares	54.28
Weighted-average grant date fair value, Awards forfeited | $ / shares	0
Weighted-average grant date fair value, Awards balance | $ / shares	$ 54.63
Weighted average remaining contractual term, Balance	2 years 3 months 18 days
Aggregate intrinsic value, Balance | $	$ 41,187	[2]

[1] Does not include employee stock purchase plans or stock option plans.

[2] The intrinsic value is calculated as the market value as of the end of the fiscal period. As reported by the NASDAQ Global Select Market, the market value as of March 30, 2018 was $78.65.