Earnings Per Share Earnings Per Share (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 27, 2011	Sep. 27, 2011	Jun. 28, 2011	Mar. 29, 2011	Dec. 28, 2010	Sep. 28, 2010	Jun. 29, 2010	Mar. 30, 2010	Dec. 27, 2011	Dec. 28, 2010	Dec. 29, 2009
Earnings Per Share [Abstract]
Net income attributable to Panera Bread Company	$ 38,620	$ 28,848	$ 35,710	$ 32,774	$ 36,520	$ 22,797	$ 26,704	$ 25,845	$ 135,952	$ 111,866	$ 86,050
Weighted Average Number of Shares Outstanding, Basic (in shares)									29,601	30,614	30,667
Incremental Common Shares Attributable to Share-based Payment Arrangements									302	308	312
Weighted Average Number of Shares Outstanding, Diluted (in shares)									29,903	30,922	30,979
Earnings Per Share, Basic (in dollars per share)	$ 1.33	$ 0.98	$ 1.20	$ 1.10	$ 1.22	$ 0.75	$ 0.86	$ 0.83	$ 4.59	$ 3.65	$ 2.81
Earnings Per Share, Diluted (in dollars per share)	$ 1.31	$ 0.97	$ 1.18	$ 1.09	$ 1.21	$ 0.75	$ 0.85	$ 0.82	$ 4.55	$ 3.62	$ 2.78