Accounts Receivable (Tables)

12 Months Ended

Dec. 31, 2018

Receivables [Abstract]

Schedule of the entity's accounts receivable balances

The following table presents details of our accounts receivable balances:

	As of December 31,
	2018			2017
	(Dollars in millions)
Trade and purchased receivables	$	491		591
Earned and unbilled receivables	92			99
Other	4			3
Total accounts receivable	587			693
Less: allowance for doubtful accounts	(41		)	(47	)
Accounts receivable, less allowance	$	546		646

Schedule of the entity's allowance for doubtful accounts

The following table presents details of our allowance for doubtful accounts:

	Beginning Balance		Additions	Deductions		Ending Balance
	(Dollars in millions)
2018	$	47	60	(66	)	41
2017	$	53	74	(80	)	47
2016	$	47	80	(74	)	53