Deferred Revenue

12 Months Ended

Dec. 31, 2018

Revenue from Contract with Customer [Abstract]

Deferred Revenue

Contract Cost AssetsAs of December 31, 2018, we had $45.8 million of contract cost assets. During the year ended December 31, 2018, we recorded no impairment losses to contract cost assets. During the year ended December 31, 2018, we recorded $36.0 million of amortization expense related to contract cost assets.Deferred Revenue

The following table presents the change in deferred revenue for the period presented (in thousands):

	Year Ended December 31, 2018
Balance as of January 1, 2018	$	31,918
Deferral of revenue	982,647
Less: Revenue recognized	(980,485		)
Balance as of December 31, 2018	$	34,080

During the year ended December 31, 2018, we recognized as revenue a total of $28.8 million pertaining to amounts that were recorded in deferred revenue as of December 31, 2017.