Stockholder's Equity (Narrative) (Details) $ / shares in Units, $ in Thousands		1 Months Ended			12 Months Ended
	Jan. 21, 2020 $ / shares shares	Dec. 29, 2019 USD ($) installment shares	Dec. 31, 2017 shares	Dec. 31, 2016 USD ($) shares	Dec. 27, 2020 shares	Dec. 29, 2019 USD ($) installment $ / shares shares	Dec. 30, 2018 USD ($) $ / shares shares	Dec. 31, 2017 USD ($) $ / shares shares	Feb. 28, 2018 installment shares	Jan. 26, 2016 shares
Preferred Stock
Preferred stock issued (in shares) | shares		0	0			0	0	0
Preferred stock, shares outstanding (in shares) | shares		0	0			0	0	0
Stock Incentive Plan
Pretax intrinsic value of options exercised						$ 82,500	$ 69,600
Intrinsic value of options outstanding		$ 431,500				431,500
Intrinsic value of options exercisable		315,200				315,200
Amount of cash received from exercise of stock options						$ 34,600	$ 37,200	$ 24,900
Period used for the exchange traded option included the longest dated options						3 months
Grant date fair value of stock options granted (in USD per share) | $ / shares						$ 72.00	$ 71.89	$ 48.45
Employee stock options
Stock Incentive Plan
Stock options maximum life						10 years
Employee and non-employee stock option
Stock Incentive Plan
Vesting period						3 years
Allocated Share-based Compensation Expense						$ 26,100	$ 19,800	$ 14,200
Nonvested awards unrecognized cost		$ 25,600				$ 25,600
Weighted average period for non-vested awards expected to be recognized						1 year 3 months 18 days
Performance Shares
Share-based compensation expense						$ 26,100	19,800	14,200
Performance shares
Stock Incentive Plan
Allocated Share-based Compensation Expense						$ 7,500	$ 5,100	4,600
Performance Shares
Performance period for judging awards						3 years
Number of equal annual installments | installment		3				3			3
Number of shares issued (in shares) | shares						8,586	6,481
Shares expected to be issued in three installments (in shares) | shares									59,427
Share-based compensation expense						$ 7,500	$ 5,100	4,600
Restricted stock
Stock Incentive Plan
Allocated Share-based Compensation Expense						3,000	2,700	2,700
Nonvested awards unrecognized cost		$ 3,300				$ 3,300
Weighted average period for non-vested awards expected to be recognized						1 year 6 months
Performance Shares
Share-based compensation expense						$ 3,000	$ 2,700	$ 2,700
Restricted Stock
Granted (in shares) | shares						17,522	16,733	24,232
Issued (in shares) | shares						(35,330)	(28,855)	(30,704)
Accelerated Share Repurchase Program
Treasury Stock
Number of shares authorized to be repurchased (in shares) | shares		3,000,000				3,000,000				3,000,000
Treasury shares, acquired (in shares) | shares						0	0	0
Non-Employee Director | Restricted stock
Stock Incentive Plan
Allocated Share-based Compensation Expense						$ 1,000	$ 1,000	$ 1,000
Grant date fair value of stock options granted (in USD per share) | $ / shares						$ 251.23	$ 193.39	$ 134.26
Performance Shares
Share-based compensation expense						$ 1,000	$ 1,000	$ 1,000
Restricted Stock
Issued (in shares) | shares						(2,840)	(5,733)	(10,305)
Non-Employee Director | Restricted stock units (RSUs)
Restricted Stock
Fair value restricted stock units granted						$ 110
First Time Director Appointed After Annual Meeting | Restricted stock units (RSUs)
Stock Incentive Plan
Vesting period						1 year
Restricted Stock
Fair value restricted stock units granted						$ 55
Chief Executive Officer | Restricted stock units (RSUs)
Stock Incentive Plan
Vesting period				3 years
Allocated Share-based Compensation Expense						600	$ 700
Performance Shares
Share-based compensation expense						$ 600	$ 700
Restricted Stock
Fair value restricted stock units granted				$ 2,000
Granted (in shares) | shares				16,045
Issued (in shares) | shares			(2,389)			(2,697)	(2,697)
Shares paid for tax withholding for share based compensation (in shares) | shares		2,651	2,960				2,651
Maximum | Chief Executive Officer | Restricted stock units (RSUs)
Stock Incentive Plan
Allocated Share-based Compensation Expense								$ 700
Performance Shares
Share-based compensation expense								$ 700
Subsequent Event | Employee stock options
Stock Incentive Plan
Stock options granted in period (in shares) | shares	245,985
Exercise price (in USD per share) | $ / shares	$ 383.33
Scenario, Forecast | Performance shares
Performance Shares
Number of shares issued (in shares) | shares					7,673