Selected Quarterly Financial Information (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Feb. 28, 2018	Nov. 30, 2017	Aug. 31, 2017	May 31, 2017	Feb. 28, 2017	Nov. 30, 2016	Aug. 31, 2016	May 31, 2016	Feb. 28, 2018	Feb. 28, 2017	Feb. 29, 2016
Summary of selected quarterly financial information
Net sales	$ 1,765.9	$ 1,799.1	$ 2,084.5	$ 1,935.5	$ 1,628.0	$ 1,810.5	$ 2,021.2	$ 1,871.8	$ 7,585.0	$ 7,331.5	$ 6,548.4
Gross profit	849.1	907.5	1,065.3	995.3	787.7	891.4	969.0	881.3	3,817.2	3,529.4	2,942.3
Net income attributable to CBI	925.5	491.1	$ 499.5	$ 402.8	452.0	$ 405.9	$ 358.9	$ 318.3	2,318.9	1,535.1	1,054.9
Earnings Per Share [Abstract]
Unrealized gain on equity securities and related activities, net income tax effect	255.4	$ 138.8
Net income tax benefit related to the Tax Cuts and Jobs Act	$ (363.0)								(363.0)	0.0	0.0
Gain on sale of business, net of income tax effect					$ 196.1
Class A Common Stock [Member]
Summary of selected quarterly financial information
Net income attributable to CBI									$ 2,063.7	$ 1,370.1	$ 940.0
Earnings Per Share [Abstract]
Net income per common share attributable to CBI, basic (in dollars per share)	$ 4.84	$ 2.54	$ 2.58	$ 2.09	$ 2.34	$ 2.04	$ 1.81	$ 1.61	$ 12.04	$ 7.79	$ 5.42
Net income per common share attributable to CBI, diluted (in dollars per share)	4.64	2.44	2.48	2.00	2.26	1.98	1.75	1.55	$ 11.55	$ 7.52	$ 5.18
Class B Convertible Common Stock [Member]
Summary of selected quarterly financial information
Net income attributable to CBI									$ 255.2	$ 165.0	$ 114.9
Earnings Per Share [Abstract]
Net income per common share attributable to CBI, basic (in dollars per share)	4.40	2.31	2.35	1.90	2.12	1.85	1.64	1.46	$ 10.93	$ 7.07	$ 4.92
Net income per common share attributable to CBI, diluted (in dollars per share)	$ 4.28	$ 2.26	$ 2.29	$ 1.85	$ 2.09	$ 1.82	$ 1.61	$ 1.43	$ 10.66	$ 6.93	$ 4.79