Selected Quarterly Financial Data Selected Quartely Financial Data (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
Selected Quarterly Financial Information [Abstract]
Revenue, Net	$ 495,765	$ 453,087	$ 451,080	$ 422,100	$ 428,161	$ 371,994	$ 378,124	$ 364,210	$ 1,822,032	$ 1,542,489	$ 1,353,494
Operating profit	62,546	47,607	57,132	52,974	60,809	35,996	46,103	42,161	220,259	185,069	140,897
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	38,620	28,848	35,710	32,774	36,384	22,715	26,655	25,845	135,952	111,599	86,851
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
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