Valuation and Qualifying Accounts (Tables)

12 Months Ended

Dec. 31, 2019

SEC Schedule, 12-09, Valuation and Qualifying Accounts [Abstract]

Schedule of Valuation and Qualifying Accounts

The table below provides changes in the allowance for doubtful accounts over each period:

(in millions)	2019			2018			2017
Balance at beginning of year	$	25		$	25		$	21
Additions charged to expense	3			5			5
Deductions/other	(3		)	(5		)	(1		)
Balance at end of year	$	25		$	25		$	25