Stock Plans (Narrative) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 04, 2021	Jul. 05, 2020	Jul. 04, 2021	Jul. 05, 2020	Jan. 03, 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total income tax benefit recognized for stock-based compensation	$ 4,100	$ 2,200
Stock-based compensation costs capitalized as part of inventory			$ 500	$ 300
Proceeds from issuance of common stock under stock plans			$ 14,185	$ 10,074
Share-based Payment Arrangement, Expense	7,204	9,603
Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted-average grant-date fair value of options			$ 65.80	$ 18.98
Total intrinsic value of options exercised	9,500	7,800
Proceeds from issuance of common stock under stock plans			$ 5,000	$ 1,100
Share-based Payment Arrangement, Expense	900	800
Total unrecognized compensation cost, net of estimated forfeitures, related to nonvested stock, granted	8,900		$ 8,900
Weighted-average period for recognition of unrecognized compensation cost, years			2 years 3 months 18 days
Restricted Stock Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Payment Arrangement, Expense	2,800	2,700
Total unrecognized compensation cost, net of estimated forfeitures, related to nonvested stock, granted	$ 23,400		$ 23,400
Weighted-average period for recognition of unrecognized compensation cost, years			1 year 9 months 18 days
Awards/units outstanding	291,000		291,000		296,000
Number of Shares, Granted			102,000
Weighted-average grant-date fair value of stock granted (per share)			$ 129.27
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period			5,000
Fair value of restricted stock awards vested	$ 8,500	1,400
Performance Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Payment Arrangement, Expense	$ 100	3,300
Awards/units outstanding	0		0
Number of Shares, Granted			0
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period			0
Stock Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Granted			0
Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares authorized under plan	5,000,000.0		5,000,000.0
Number of Shares, Granted			58	13,612
Weighted-average grant-date fair value of stock granted (per share)			$ 136.33	$ 92.25
Shares available for grant under employee stock purchase plan	800,000		800,000
Performance Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Payment Arrangement, Expense	$ 1,400	$ 2,000
Awards/units outstanding	128,386		128,386
Number of Shares, Granted			77,373
Weighted-average grant-date fair value of stock granted (per share)			$ 113.44
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period			0