Earnings Per Share Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 27, 2016	Sep. 27, 2016	Jun. 28, 2016	Mar. 29, 2016	Dec. 29, 2015	Sep. 29, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 27, 2016	Dec. 29, 2015	Dec. 30, 2014
Earnings Per Share [Abstract]
Net income attributable to Panera Bread Company	$ 44,010	$ 31,975	$ 34,501	$ 35,088	$ 43,160	$ 32,393	$ 41,929	$ 31,860	$ 145,574	$ 149,342	$ 179,293
Weighted Average Number of Shares Outstanding, Basic (in shares)									23,444	25,685	26,881
Incremental Common Shares Attributable to Dilutive Effect of Share-based Payment Arrangements									121	103	118
Weighted Average Number of Shares Outstanding, Diluted (in shares)									23,565	25,788	26,999
Earnings Per Share, Basic (in dollars per share)	$ 1.93	$ 1.37	$ 1.46	$ 1.46	$ 1.75	$ 1.28	$ 1.60	$ 1.20	$ 6.21	$ 5.81	$ 6.67
Earnings Per Share, Diluted (in dollars per share)	$ 1.92	$ 1.37	$ 1.46	$ 1.45	$ 1.74	$ 1.27	$ 1.60	$ 1.20	$ 6.18	$ 5.79	$ 6.64