Income Taxes (Deferred Tax Assets and Liabilities) (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Deferred tax assets (liabilities):
Stock-based compensation	$ 258,376	$ 190,451
Federal and California tax R&D credits	408,715	369,023
Foreign tax credits	137,818	218,026
Accruals and reserves	42,450	36,396
Operating leases	349,208	0
Other	6,510	27,203
Gross deferred tax assets	1,203,077	841,099
Depreciation & amortization	(80,921)	(151,678)
Operating leases	(329,168)	0
Gross deferred tax liabilities	410,089	151,678
Valuation allowance	(134,782)	(124,996)
Net deferred tax assets	$ 658,206	$ 564,425