Other Receivables (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Accounts, Notes, Loans and Financing Receivable [Line Items]
Other receivables	$ 469,796	$ 399,262
Supplier rebates and non-trade receivables
Accounts, Notes, Loans and Financing Receivable [Line Items]
Other receivables	334,156	295,292
Medicare bad debt claims
Accounts, Notes, Loans and Financing Receivable [Line Items]
Other receivables	$ 135,640	$ 103,970