Income Taxes (Components of Deferred Tax Assets and Liabilities) (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Deferred tax assets:
Accruals and reserves	$ 53,465	$ 27,022
Deferred revenue	58,977	62,085
Tax credits	107,046	81,720
Net operating losses	56,156	54,747
Stock based compensation	40,182	30,936
Swiss tax reform	245,554	0
Valuation allowance	(128,388)	(85,400)
Total deferred tax assets	432,992	171,110
Deferred tax liabilities:
Acquired technology	(3,521)	(15,681)
Depreciation and amortization	(34,653)	(5,044)
Prepaid expenses	(29,775)	(23,213)
Other	(5,859)	(5,249)
Total deferred tax liabilities	(73,808)	(49,187)
Total net deferred tax assets	$ 359,184	$ 121,923