Accounts Receivable, Accounts Payable and Accrued Liabilities (Tables)

12 Months Ended

Dec. 31, 2018

Accounts Receivable Accounts Payable And Accrued Liabilities [Abstract]

Schedule of Accounts Receivable

Accounts receivable consist of the following:

	As of December 31
(in thousands)	2018		2017
Receivables from contracts with customers, less doubtful accounts of $14,775 and $22,975	$	538,021	$	600,215
Other receivables	44,259		20,104
	$	582,280	$	620,319

Schedule of Changes in Allowance for Doubtful Accounts

The changes in allowance for doubtful accounts was as follows:

(in thousands)	Balance at Beginning of Period		Additions – Charged to Costs and Expenses		Deductions			Balance at End of Period
2018	$	22,975	$	10,209	$	(18,409	)	$	14,775
2017	$	26,723	$	33,830	$	(37,578	)	$	22,975
2016	$	27,854	$	29,718	$	(30,849	)	$	26,723

Schedule of Accounts Payable and Accrued Liabilities

Accounts payable and accrued liabilities consist of the following:

	As of December 31
(in thousands)	2018		2017
Accounts payable and accrued liabilities	$	337,123	$	385,927
Accrued compensation and related benefits	149,455		140,396
	$	486,578	$	526,323