Shareholders' Equity Stock Options (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 29, 2012		Dec. 31, 2011		Jan. 01, 2011
Stock Option Valuation Assumptions [Abstract]
Fair value assumptions, method used	Black-Scholes-Merton option-pricing model
Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock Options, Award Vesting Rights	vest proportionally over periods of two to four years from the grant-date
Stock Options, Expiration Period	ten years
Stock options activity [Roll Forward]
Stock options - outstanding beginning of period	3,305
Stock options - granted during period	267
Stock options - exercised during period	(679)
Stock options - canceled/forfeited during period	(4)
Stock options - outstanding end of period	2,889		3,305
Stock options - exercisable at end of period	2,250
Vested and expected to vest - outstanding	2,830
Stock options activity - other information [Abstract]
Stock options - weighted average exercise price per share, outstanding	$ 15.92		$ 13.36
Stock options - weighted average exercise price per share, granted	$ 28.32
Stock options - weighted average exercise price per share, exercised	$ 8.32
Stock options - weighted average exercise price per share, forfeited/canceled	$ 22.32
Stock options - weighted average exercise price per share, exercisable	$ 15.86
Stock options - weighted average exercise price per share, vested and expected to vest	$ 15.93
Stock options - weighted average remaining contractual term (years) outstanding	5 years		5 years 4 months 24 days
Stock options - weighted average remaining contractual terms (years) exercisable	4 years 2 months 12 days
Stock options - weighted average remaining contractual term (years) vested and expected to vest	5 years
Stock options - aggregate intrinsic value outstanding	$ 26,109	[1]	$ 29,907	[1]
Stock options - aggregate intrinsic value exercisable	19,917	[1]
Stock options - aggregate intrinsic value vested and expected to vest	25,496	[1]
Other information - options [Abstract]
Weighted-average grant date fair value of stock options granted	$ 14.28		$ 10.91		$ 6.18
Total intrinsic value (at exercise) of stock options exercised	12,724		8,295		5,860
Proceeds from Stock Options Exercised	5,100
Employee Service Share-based Compensation, Tax Benefit Realized from Exercise of Stock Options	4,900
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized	$ 4,310
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized, Period for Recognition	2 years 7 months 6 days
Stock Option Valuation Assumptions [Abstract]
Expected dividend yield (in hundredths)	0.00%		0.00%		0.00%
Expected volatility (in hundredths)	63.00%		78.00%		78.00%
Risk-free interest rate (in hundredths)	1.10%		1.90%		2.00%
Expected term (in years)	5 years 7 months		5 years		4 years 10 months 24 days

[1] Aggregate intrinsic value includes only those options where the current share price is equal to or greater than the share price on the date of grant.