Deferred Revenue (Tables)

3 Months Ended

Mar. 31, 2019

Revenue from Contract with Customer [Abstract]

Schedule of Changes in Deferred Revenue

The changes in our deferred revenue during the three months endedMarch 31, 2019 are as follows (in millions):

	Annual Listings Revenues			Original Listings Revenues			Other Listings Revenues			Data Services and Other Revenues			Total
Deferred revenue balance at December 31, 2018	$	—		$	25		$	100		$	92		$	217
Additions	382			3			20			139			544
Amortization	(96		)	(6		)	(9		)	(85		)	(196		)
Deferred revenue balance at March 31, 2019	$	286		$	22		$	111		$	146		$	565

The changes in our deferred revenue during the three months endedMarch 31, 2018 are as follows (in millions):

	Annual Listings Revenues			Original Listings Revenues			Other Listings Revenues			Data Services and Other Revenues			Total
Deferred revenue balance at December 31, 2017	$	—		$	25		$	98		$	93		$	216
Additions	380			7			15			147			549
Amortization	(95		)	(6		)	(8		)	(96		)	(205		)
Deferred revenue balance at March 31, 2018	$	285		$	26		$	105		$	144		$	560