Accumulated Other Comprehensive Income - Reclassifications Out of Accumulated Other Comprehensive Income (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net revenues	$ 2,613	$ 2,409	$ 2,328	$ 2,217	$ 2,395	$ 2,217	$ 2,230	$ 2,137	$ 9,567	$ 8,979	$ 8,592
Cost of net revenues									2,222	2,007	1,771
Sales and marketing									2,515	2,368	2,267
Product development									1,224	1,114	923
General and administrative									1,031	900	1,122
Interest and other, net									11	1,326	209
Income from continuing operations before income taxes									2,276	3,651	2,406
Income tax benefit (provision)									(3,288)	3,634	(459)
Income (loss) from continuing operations	(2,597)	523	27	1,035	5,948	418	437	482	(1,012)	7,285	1,947
Income (loss) from discontinued operations, net of income taxes	(4)	0	0	0	(12)	(5)	(2)	0	(4)	(19)	(222)
Net income (loss)	$ (2,601)	$ 523	$ 27	$ 1,035	$ 5,936	$ 413	$ 435	$ 482	(1,016)	7,266	$ 1,725
Total reclassifications for the period									14	926
Amount of Gain (Loss) Reclassified from AOCI | Gains (losses) on cash flow hedges - foreign exchange contracts | Foreign Exchange Contract
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net revenues									(28)	0
Cost of net revenues									3	4
Sales and marketing									1	0
Product development									5	2
General and administrative									2	1
Interest and other, net									24	101
Income from continuing operations before income taxes									7	108
Income tax benefit (provision)									0	0
Income (loss) from continuing operations									7	108
Income (loss) from discontinued operations, net of income taxes									0	0
Total reclassifications for the period									7	108
Amount of Gain (Loss) Reclassified from AOCI | Unrealized gains (losses) on investments
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest and other, net									7	1,299
Income from continuing operations before income taxes									7	1,299
Income tax benefit (provision)									0	(481)
Total reclassifications for the period									$ 7	$ 818