SCHEDULE II - VALUATION AND QUALIFYING ACCOUNTS

12 Months Ended

Dec. 31, 2018

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

SCHEDULE II - VALUATION AND QUALIFYING ACCOUNTS

SCHEDULE II — VALUATION AND QUALIFYING ACCOUNTS

(in millions)	Balance at Beginning of Year		Charged to Costs and Expenses		Charged to Other Accounts			Deductions			Balance at End of Year
Year ended December 31, 2018
Allowance for doubtful accounts	$	97	$	4	$	(4	)	$	(50	)	$	47
Deferred tax asset valuation allowance	$	2,001	$	870	$	42		$	—		$	2,913
Year ended December 31, 2017
Allowance for doubtful accounts	$	80	$	33	$	4		$	(20	)	$	97
Deferred tax asset valuation allowance	$	1,857	$	221	$	(77	)	$	—		$	2,001
Year ended December 31, 2016
Allowance for doubtful accounts	$	67	$	57	$	(22	)	$	(22	)	$	80
Deferred tax asset valuation allowance	$	1,367	$	627	$	(137	)	$	—		$	1,857

With respect to the deferred tax valuation allowance, the amounts in 2016, 2017 and 2018 charged to other accounts primarily relates to foreign currency fluctuations on debt.