Summary of Significant Accounting Policies - Revenue Recognition, Vendor Rebates and Promotional Allowances, and Excise Taxes (Details) - USD ($) $ 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
Accounting Policies [Abstract]
Management service fee revenue as a percentage of total net sales, less than 1%									1.00%	1.00%	1.00%
Vendor rebates and promotional allowances									$ 254.7	$ 237.7	$ 231.9
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
Excise taxes as a percentage of net sales									20.00%	21.00%	22.00%
Excise taxes as a percentage of cost of goods sold									21.00%	22.00%	23.00%