Income Taxes (Reconciliation of Provision for Income Taxes) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Expected tax expense at U.S. Federal statutory rates	$ 257,556	$ 169,860	$ 91,179
State income taxes, net of Federal income tax effect	33,611	6,404	7,261
Foreign earnings at other than U.S. rates	63,519	(87,514)	14,639
Federal and California R&D tax credits	(140,749)	(79,868)	(41,144)
Excess tax benefits on stock-based compensation	(191,323)	(157,888)	0
Rate Change / Transition Tax	(71,516)	79,077	0
U.S. Minimum Tax on Foreign Entities	43,099	0	0
Nondeductible Officers Compensation	14,377	28	28
Other	6,642	(3,707)	1,866
Provision for (benefit from) income taxes	$ 15,216	$ (73,608)	$ 73,829
Effective Tax Rate	1.00%	(15.00%)	28.00%