Reclassification (Details) - USD ($) $ in Thousands	3 Months Ended												12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	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, 2018	Dec. 31, 2017	Dec. 31, 2016
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Revenues	$ 4,186,841	$ 3,999,374	$ 3,907,270	$ 3,700,856	$ 3,285,755	$ 2,984,859	$ 2,785,464	$ 2,636,635	$ 2,477,541	$ 2,290,188	$ 2,105,204	$ 1,957,736	$ 15,794,341	$ 11,692,713	$ 8,830,669
Cost of revenues		2,531,128	2,402,431	2,300,579	2,214,334	2,086,239	1,991,696	1,740,731	1,719,716	1,593,768	1,525,397	1,418,581	9,967,538	8,033,000	6,257,462
Marketing		510,330	592,007	536,777	466,527	352,446	311,160	306,148	314,447	311,017	240,590	231,465	2,369,469	1,436,281	1,097,519
Technology and development		308,620	299,095	282,310	247,132	230,223	242,484	233,871	205,912	197,506	190,204	186,610	1,221,814	953,710	780,232
General and administrative		168,628	151,524	134,612	112,459	107,324	112,317	98,943	83,532	81,861	78,643	71,627	630,294	431,043	315,663
Operating income		480,668	462,213	446,578	245,303	208,627	127,807	256,942	153,934	106,036	70,370	49,453	1,605,226	838,679	379,793
Contribution profit (loss)													3,457,334	2,223,432	1,475,688
Domestic Streaming
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Revenues		1,937,314	1,893,222	1,820,019	1,630,274	1,547,210	1,505,499	1,470,042	1,403,462	1,304,333	1,208,271	1,161,241	7,646,647	6,153,025	5,077,307
Cost of revenues		1,038,473	969,995	936,480	916,100	902,275	868,530	783,954	788,598	746,220	729,399	687,756	4,038,394	3,470,859	2,951,973
Marketing		210,595	251,298	250,719	211,057	141,533	124,903	126,253	113,916	116,687	93,751	88,574	1,025,351	603,746	412,928
Contribution profit (loss)		$ 688,246	$ 671,929	$ 632,820	$ 503,117	$ 503,402	$ 512,066	$ 559,835	$ 500,948	$ 441,426	$ 385,121	$ 384,911	2,582,902	$ 2,078,420	$ 1,712,406
Contribution margin		35.50%	35.50%	34.80%	30.90%	32.50%	34.00%	38.10%	35.70%	33.80%	31.90%	33.10%		33.80%	33.70%
International Streaming
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Revenues		$ 1,973,283	$ 1,921,144	$ 1,782,086	$ 1,550,329	$ 1,327,435	$ 1,165,228	$ 1,046,199	$ 947,666	$ 853,480	$ 758,201	$ 651,748	7,782,105	$ 5,089,191	$ 3,211,095
Cost of revenues		1,455,554	1,392,512	1,321,706	1,255,749	1,136,877	1,070,432	896,558	872,972	783,877	728,168	657,730	5,776,047	4,359,616	3,042,747
Marketing		299,735	340,709	286,058	255,470	210,913	186,257	179,895	200,531	194,330	146,839	142,891	1,344,118	832,535	684,591
Contribution profit (loss)		$ 217,994	$ 187,923	$ 174,322	$ 39,110	$ (20,355)	$ (91,461)	$ (30,254)	$ (125,837)	$ (124,727)	$ (116,806)	$ (148,873)	$ 661,940	$ (102,960)	$ (516,243)
Contribution margin		11.00%	9.80%	9.80%	2.50%	(1.50%)	(7.80%)	(2.90%)	(13.30%)	(14.60%)	(15.40%)	(22.80%)		(2.00%)	(16.10%)
As Previously Reported
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Revenues		$ 3,999,374	$ 3,907,270	$ 3,700,856	$ 3,285,755	$ 2,984,859	$ 2,785,464	$ 2,636,635	$ 2,477,541	$ 2,290,188	$ 2,105,204	$ 1,957,736		$ 11,692,713	$ 8,830,669
Cost of revenues		2,412,346	2,289,867	2,196,075	2,107,354	1,992,980	1,902,308	1,657,024	1,654,419	1,532,844	1,473,098	1,369,540		7,659,666	6,029,901
Marketing		435,269	526,780	479,222	419,939	312,490	274,323	271,270	284,996	282,043	216,029	208,010		1,278,022	991,078
Technology and development		327,026	317,213	300,730	273,351	255,236	267,083	257,108	225,191	216,099	207,300	203,508		1,052,778	852,098
General and administrative		344,065	311,197	278,251	239,808	215,526	213,943	194,291	159,001	153,166	138,407	127,225		863,568	577,799
Operating income		480,668	462,213	446,578	245,303	208,627	127,807	256,942	153,934	106,036	70,370	49,453		838,679	379,793
As Previously Reported | Domestic Streaming
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Revenues		1,937,314	1,893,222	1,820,019	1,630,274	1,547,210	1,505,499	1,470,042	1,403,462	1,304,333	1,208,271	1,161,241		6,153,025	5,077,307
Cost of revenues		991,823	925,703	894,873	873,372	864,408	831,962	749,488	761,479	720,658	707,106	666,546		3,319,230	2,855,789
Marketing		183,521	227,961	228,022	195,784	128,901	113,608	115,038	105,589	108,495	86,806	81,942		553,331	382,832
Contribution profit (loss)		$ 761,970	$ 739,558	$ 697,124	$ 561,118	$ 553,901	$ 559,929	$ 605,516	$ 536,394	$ 475,180	$ 414,359	$ 412,753		$ 2,280,464	$ 1,838,686
Contribution margin		39.30%	39.10%	38.30%	34.40%	35.80%	37.20%	41.20%	38.20%	36.40%	34.30%	35.50%		37.10%	36.20%
As Previously Reported | International Streaming
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Revenues		$ 1,973,283	$ 1,921,144	$ 1,782,086	$ 1,550,329	$ 1,327,435	$ 1,165,228	$ 1,046,199	$ 947,666	$ 853,480	$ 758,201	$ 651,748		$ 5,089,191	$ 3,211,095
Cost of revenues		1,383,422	1,324,240	1,258,809	1,191,497	1,081,485	1,017,612	847,317	834,794	748,515	698,162	629,899		4,137,911	2,911,370
Marketing		251,748	298,819	251,200	224,155	183,589	160,715	156,232	179,407	173,548	129,223	126,068		724,691	608,246
Contribution profit (loss)		$ 338,113	$ 298,085	$ 272,077	$ 134,677	$ 62,361	$ (13,099)	$ 42,650	$ (66,535)	$ (68,583)	$ (69,184)	$ (104,219)		$ 226,589	$ (308,521)
Contribution margin		17.10%	15.50%	15.30%	8.70%	4.70%	(1.10%)	4.10%	(7.00%)	(8.00%)	(9.10%)	(16.00%)		4.50%	(9.60%)
Reclassifications
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Revenues		$ 0	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0		$ 0	$ 0
Cost of revenues		118,782	112,564	104,504	106,980	93,259	89,388	83,707	65,297	60,924	52,299	49,041		373,334	227,561
Marketing		75,061	65,227	57,555	46,588	39,956	36,837	34,878	29,451	28,974	24,561	23,455		158,259	106,441
Technology and development		(18,406)	(18,118)	(18,420)	(26,219)	(25,013)	(24,599)	(23,237)	(19,279)	(18,593)	(17,096)	(16,898)		(99,068)	(71,866)
General and administrative		(175,437)	(159,673)	(143,639)	(127,349)	(108,202)	(101,626)	(95,348)	(75,469)	(71,305)	(59,764)	(55,598)		(432,525)	(262,136)
Operating income		0	0	0	0	0	0	0	0	0	0	0		0	0
Reclassifications | Domestic Streaming
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Revenues		0	0	0	0	0	0	0	0	0	0	0		0	0
Cost of revenues		46,650	44,292	41,607	42,728	37,867	36,568	34,466	27,119	25,562	22,293	21,210		151,629	96,184
Marketing		27,074	23,337	22,697	15,273	12,632	11,295	11,215	8,327	8,192	6,945	6,632		50,415	30,096
Contribution profit (loss)		(73,724)	(67,629)	(64,304)	(58,001)	(50,499)	(47,863)	(45,681)	(35,446)	(33,754)	(29,238)	(27,842)		(202,044)	(126,280)
Reclassifications | International Streaming
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Revenues		0	0	0	0	0	0	0	0	0	0	0		0	0
Cost of revenues		72,132	68,272	62,897	64,252	55,392	52,820	49,241	38,178	35,362	30,006	27,831		221,705	131,377
Marketing		47,987	41,890	34,858	31,315	27,324	25,542	23,663	21,124	20,782	17,616	16,823		107,844	76,345
Contribution profit (loss)		$ (120,119)	$ (110,162)	$ (97,755)	$ (95,567)	$ (82,716)	$ (78,362)	$ (72,904)	$ (59,302)	$ (56,144)	$ (47,622)	$ (44,654)		$ (329,549)	$ (207,722)