Stock-Based Compensation (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended	0 Months Ended					3 Months Ended	1 Months Ended
	Mar. 31, 2013	Dec. 28, 2012 Class B common stock	Dec. 02, 2011 Class B common stock	Dec. 28, 2012 Class A common stock	Dec. 02, 2011 Class A common stock	Mar. 31, 2013 Class A common stock	Mar. 31, 2013 Stock options	Jan. 31, 2013 Stock option adjustment employee
Share-based compensation
Maximum Expiration term							10 years
Percentage of stock awards vesting per year	20.00%
Shares of common stock available for future grant under stock incentive plans						70.0
Number of stock options subject to an exercise price change in connection with the Stock Option Adjustment (in shares)								16.3
Dividend in cash per share		$ 1.00	$ 2.00	$ 1.00	$ 2.00
Number of employees affected by stock option adjustment								550
Reduction in exercise price due to dividend declaration (in dollars per share)								$ 0.77