Stockholders' Equity (Details) (USD $) In Thousands	3 Months Ended		9 Months Ended
	Sep. 27, 2011	Sep. 28, 2010	Sep. 27, 2011	Sep. 28, 2010
Summary of changes in shareholders' equity
Beginning Balance			$ 595,608	$ 597,036
Comprehensive income:
Net income	28,848	22,715	97,332	75,211
Other comprehensive income:
Foreign currency translation adjustment			39	47
Total other comprehensive income			39	47
Comprehensive income			97,371	75,258
Noncontrolling interest in PB Biscuit				630
Issuance of common stock			1,532	1,364
Exercise of employee stock options			2,183	24,327
Stock-based compensation expense			7,506	7,112
Repurchase of common stock			93,647	153,376
Tax benefit from exercise of stock options			3,934	5,950
Ending Balance	614,487	558,301	614,487	558,301
Comprehensive Income (loss) [Member]
Comprehensive income:
Net income			97,332	75,211
Other comprehensive income:
Foreign currency translation adjustment			39	47
Total other comprehensive income			39	47
Comprehensive income			97,371	75,258
Common Stock Class A [Member] | Common Stock [Member]
Summary of changes in shareholders' equity
Beginning Balance			3	3
Comprehensive income:
Net income			0	0
Other comprehensive income:
Foreign currency translation adjustment			0	0
Noncontrolling interest in PB Biscuit				0
Issuance of common stock			0	0
Exercise of employee stock options			0	0
Stock-based compensation expense			0	0
Repurchase of common stock			0	0
Tax benefit from exercise of stock options			0	0
Ending Balance	3	3	3	3
Common Stock Class B [Member] | Common Stock [Member]
Summary of changes in shareholders' equity
Beginning Balance			0	0
Comprehensive income:
Net income			0	0
Other comprehensive income:
Foreign currency translation adjustment			0	0
Noncontrolling interest in PB Biscuit				0
Issuance of common stock			0	0
Exercise of employee stock options			0	0
Stock-based compensation expense			0	0
Repurchase of common stock			0	0
Tax benefit from exercise of stock options			0	0
Ending Balance	0	0	0	0
Treasury Stock [Member]
Summary of changes in shareholders' equity
Beginning Balance			(78,990)	(3,928)
Comprehensive income:
Net income			0	0
Other comprehensive income:
Foreign currency translation adjustment			0	0
Noncontrolling interest in PB Biscuit				0
Issuance of common stock			0	0
Exercise of employee stock options			0	0
Stock-based compensation expense			0	0
Repurchase of common stock			93,647	74,946
Tax benefit from exercise of stock options			0	0
Ending Balance	(172,637)	(78,874)	(172,637)	(78,874)
Additional Paid-in Capital [Member]
Summary of changes in shareholders' equity
Beginning Balance			130,005	168,288
Comprehensive income:
Net income			0	0
Other comprehensive income:
Foreign currency translation adjustment			0	0
Noncontrolling interest in PB Biscuit				0
Issuance of common stock			1,532	1,364
Exercise of employee stock options			2,183	24,327
Stock-based compensation expense			7,506	7,112
Repurchase of common stock			0	78,430
Tax benefit from exercise of stock options			3,934	5,950
Ending Balance	145,160	128,611	145,160	128,611
Retained Earnings [Member]
Summary of changes in shareholders' equity
Beginning Balance			544,315	432,449
Comprehensive income:
Net income			97,332	75,342
Other comprehensive income:
Foreign currency translation adjustment			0	0
Noncontrolling interest in PB Biscuit				0
Issuance of common stock			0	0
Exercise of employee stock options			0	0
Stock-based compensation expense			0	0
Repurchase of common stock			0	0
Tax benefit from exercise of stock options			0	0
Ending Balance	641,647	507,791	641,647	507,791
Accumulated Other Comprehensive Income (loss) [Member]
Summary of changes in shareholders' equity
Beginning Balance			275	224
Comprehensive income:
Net income			0	0
Other comprehensive income:
Foreign currency translation adjustment			39	47
Noncontrolling interest in PB Biscuit				0
Issuance of common stock			0	0
Exercise of employee stock options			0	0
Stock-based compensation expense			0	0
Repurchase of common stock			0	0
Tax benefit from exercise of stock options			0	0
Ending Balance	314	271	314	271
Noncontrolling Interest [Member]
Summary of changes in shareholders' equity
Beginning Balance			0	0
Comprehensive income:
Net income			0	(131)
Other comprehensive income:
Foreign currency translation adjustment			0	0
Noncontrolling interest in PB Biscuit				630
Issuance of common stock			0	0
Exercise of employee stock options			0	0
Stock-based compensation expense			0	0
Repurchase of common stock			0	0
Tax benefit from exercise of stock options			0	0
Ending Balance	$ 0	$ 499	$ 0	$ 499