Quarterly Financial Data (Unaudited) (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Quarterly Financial Information [Line Items]
Net sales	$ 4,154.8	$ 4,422.6	$ 4,339.0	$ 3,754.1	$ 4,089.7	$ 4,273.2	$ 4,226.5	$ 3,805.9	$ 16,670.5	$ 16,395.3	$ 15,687.6
Cost of goods sold	3,924.3	4,176.0	4,100.1	3,545.9	3,872.7	4,039.4	4,009.6	3,606.1	15,746.3	15,527.8	14,895.9
Gross profit	230.5	246.6	238.9	208.2	217.0	233.8	216.9	199.8	924.2	867.5	791.7
Warehousing and distribution expenses	140.2	148.6	143.2	134.2	136.4	137.6	134.3	132.3	566.2	540.6	504.1
Selling, general and administrative expenses	63.1	61.8	64.6	65.9	61.2	58.8	61.7	63.4	255.4	245.1	224.3
Amortization of intangible assets	2.3	2.3	2.7	2.7	2.4	2.5	2.6	2.5	10.0	10.0	8.5
Total operating expenses	205.6	212.7	210.5	202.8	200.0	198.9	198.6	198.2	831.6	795.7	736.9
Income from operations	24.9	33.9	28.4	5.4	17.0	34.9	18.3	1.6	92.6	71.8	54.8
Interest expense, net	(3.6)	(4.2)	(3.2)	(3.4)	(3.1)	(3.4)	(3.4)	(3.8)	(14.4)	(13.7)	(11.0)
Foreign currency transaction (losses) gains, net	(0.5)	0.9	(1.0)	(0.2)	1.3	(0.4)	0.5	0.4	(0.8)	1.8	1.8
Income before income taxes	20.8	30.6	24.2	1.8	15.2	31.1	15.4	(1.8)	77.4	59.9	28.4
Income tax provision	(4.6)	(8.1)	(6.5)	(0.5)	(3.1)	(7.4)	(4.4)	0.5	(19.7)	(14.4)	5.1
Net income	$ 16.2	$ 22.5	$ 17.7	$ 1.3	$ 12.1	$ 23.7	$ 11.0	$ (1.3)	$ 57.7	$ 45.5	$ 33.5
Basic net income per common share (in dollars per share)	$ 0.35	$ 0.49	$ 0.39	$ 0.03	$ 0.26	$ 0.52	$ 0.24	$ (0.03)	$ 1.26	$ 0.99	$ 0.72
Diluted net income per common share (in dollars per share)	$ 0.35	$ 0.49	$ 0.38	$ 0.03	$ 0.26	$ 0.51	$ 0.24	$ (0.03)	$ 1.25	$ 0.99	$ 0.72
Weighted-average common shares outstanding (in shares)	45.7	45.8	45.9	45.9	45.7	45.9	46.0	46.2	45.7	46.0	46.3
Weighted-average shares assuming dilution (in shares)	46.0	46.1	46.1	46.0	46.0	46.2	46.1	46.2	46.0	46.1	46.4
Excise taxes	$ 819.7	$ 884.1	$ 868.8	$ 768.7	$ 859.0	$ 920.7	$ 900.4	$ 811.3	$ 3,300.0	$ 3,500.0	$ 3,500.0
LIFO expense	5.9	7.3	7.4	7.0	5.2	7.2	6.9	5.9	27.6	25.2	21.5
Depreciation and amortization	15.1	14.9	15.5	15.4	15.0	14.9	14.7	14.9	60.9	59.5	54.4
Stock-based compensation	2.4	3.1	2.2	1.9	1.8	2.0	2.5	1.9	9.6	8.2	5.0
Capital expenditures	7.5	6.1	4.1	5.1	5.2	5.7	2.3	6.9	22.8	20.1	48.2
Business integration costs										2.7
Selling, general & administrative expenses					1.4	0.9	0.1	0.3
Cigarettes
Quarterly Financial Information [Line Items]
Net sales	2,711.2	2,880.0	2,834.0	2,467.5	2,719.7	2,874.6	2,842.7	2,537.5	10,892.7	10,974.5	10,887.4
Cigarette inventory holding gains	10.1	0.3	3.8	8.8	3.1	5.9	3.5	7.1
Cigarette tax stamp inventory holding gains					0.0	7.4	0.0	0.0
Food/non-food
Quarterly Financial Information [Line Items]
Net sales	1,443.6	1,542.6	1,505.0	1,286.6	$ 1,370.0	$ 1,398.6	$ 1,383.8	$ 1,268.4	5,777.8	5,420.8	4,800.2
Candy
Quarterly Financial Information [Line Items]
Net sales									1,039.0	$ 992.0	$ 833.4
Cigarette inventory holding gains	$ 1.1	$ 5.8	$ 0.0	$ 0.0
United States | Candy
Quarterly Financial Information [Line Items]
Cigarette inventory holding gains									$ 6.9