Selected Quarterly Financial Information (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	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
Revenue:
Product	$ 407,195	$ 380,344	$ 353,904	$ 291,367	$ 289,008	$ 254,238	$ 235,616	$ 212,475	$ 1,432,810	$ 991,337	$ 744,877
Service	60,672	57,289	51,307	44,108	38,961	36,023	33,125	29,721	213,376	137,830	92,714
Total revenue	467,867	437,633	405,211	335,475	327,969	290,261	268,741	242,196	1,646,186	1,129,167	837,591
Cost of revenue:
Product	147,919	145,874	134,406	109,836	108,057	94,777	88,021	78,913	538,035	369,768	263,585
Service	12,783	11,142	11,028	11,429	9,757	9,064	9,269	8,193	46,382	36,283	30,446
Total cost of revenue	160,702	157,016	145,434	121,265	117,814	103,841	97,290	87,106
Gross profit	307,165	280,617	259,777	214,210	210,155	186,420	171,451	155,090	1,061,769	723,116	543,560
Operating expenses:
Research and development	107,180	79,610	81,194	81,610	71,398	70,648	69,020	62,515	349,594	273,581	209,448
Sales and marketing	38,808	40,640	38,630	37,027	38,321	33,216	31,744	27,606	155,105	130,887	109,084
General and administrative	21,789	19,535	23,319	22,155	22,941	19,535	17,529	15,234	86,798	75,239	75,720
Total operating expenses	167,777	139,785	143,143	140,792	132,660	123,399	118,293	105,355	591,497	479,707	394,252
Income from operations	139,388	140,832	116,634	73,418	77,495	63,021	53,158	49,735	470,272	243,409	149,308
Other income (expense), net:
Interest expense	(741)	(701)	(623)	(715)	(918)	(735)	(732)	(751)	(2,780)	(3,136)	(3,152)
Other income (expense), net	2,988	2,136	1,119	1,025	560	639	416	337	7,268	1,952	(147)
Total other income (expense), net	2,247	1,435	496	310	(358)	(96)	(316)	(414)	4,488	(1,184)	(3,299)
Income before income taxes	141,635	142,267	117,130	73,728	77,137	62,925	52,842	49,321	474,760	242,225	146,009
Provision for income taxes	37,802	8,545	14,445	(9,233)	18,354	11,668	13,938	14,076	51,559	58,036	24,907
Net income	$ 103,833	$ 133,722	$ 102,685	$ 82,961	$ 58,783	$ 51,257	$ 38,904	$ 35,245	$ 423,201	$ 184,189	$ 121,102
Net income attributable to common stockholders:
Basic (in dollars per share)	$ 1.42	$ 1.84	$ 1.42	$ 1.16	$ 0.84	$ 0.74	$ 0.57	$ 0.52	$ 5.85	$ 2.66	$ 1.81
Diluted (in dollars per share)	$ 1.29	$ 1.68	$ 1.30	$ 1.07	$ 0.79	$ 0.69	$ 0.53	$ 0.48	$ 5.35	$ 2.50	$ 1.67
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Excess tax benefits included in income taxes	$ 38,300	$ 23,800	$ 19,100	$ 28,800					$ 110,000
Provisional tax amounts from Tax Act	$ 51,800								$ 51,800