Revenue (Tables)

9 Months Ended

Sep. 30, 2018

Revenue from Contract with Customer [Abstract]

Accounts Receivables and Current and Long-Term Contract Assets and Liabilities

The Company’s Accounts receivable and current and long-term contract assets and liabilities are summarized in the following table.

(Thousands of dollars)
	Accounts Receivable, Less Allowance		Contract Assets (Current)		Contract Assets (Long-Term)		Contract Liabilities (Current)		Contract Liabilities (Long-Term)
Balance at January 1, 2018	$	2,104,555	$	33,031	$	135,150	$	208,909	$	8,745
Balance at September 30, 2018	2,584,280		59,872		172,912		245,803		8,745