Stockholders' Equity - Accumulated Other Comprehensive Loss Primarily Comprised of Accumulated Foreign Currency Translation (Details) - USD ($) $ in Millions		Dec. 31, 2019	Dec. 31, 2018
Accumulated Other Comprehensive Income Loss [Line Items]
Total accumulated other comprehensive loss	[1]	$ (63)	$ (62)
Cumulative Foreign Currency Translation Adjustments, Net of Tax
Accumulated Other Comprehensive Income Loss [Line Items]
Total accumulated other comprehensive loss	[2]	$ (63)	$ (62)

[1] Our accumulated net unrealized gain (loss) on available for sale debt securities was not material as of December 31, 2018.

[2] Through the year ended December 31, 2018, foreign currency translation adjustments excluded a provision for U.S. federal and state income taxes as a result of the Company's intention to indefinitely reinvest the earnings of its international subsidiaries outside of the United States. In response to increased cash requirements in the U.S. related to the Company’s declaration of a special cash dividend and other strategic initiatives during the fourth quarter of 2019, we determined that we no longer consider certain foreign earnings to be indefinitely reinvested. The deferred income tax liability related to foreign currency translation adjustments is not material.