Disaggregation of Revenue - Revenue by geographic location (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Disaggregation of Revenue
Revenue	$ 12,727,629	$ 12,622,893	$ 13,362,139
United States
Disaggregation of Revenue
Revenue	12,692,940	12,581,855	13,319,091
Canada and Mexico
Disaggregation of Revenue
Revenue	$ 34,689	$ 41,038	$ 43,048

Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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+ Details