Comprehensive Income (Reclassifications out of Accumulated Other Comprehensive Loss) (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2019	Mar. 31, 2018
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Unrealized net gains on available-for-sale securities		$ (3,699)	$ 3,012
Operating expenses		488,826	423,343
Net income		(110,348)	$ (144,259)
Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net income		336
Unrealized Net Losses on Available-for-sale Securities [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Unrealized net gains on available-for-sale securities		(558)
Unrealized Net Gains on Cash Flow Hedges [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Operating expenses	[1]	$ 894

[1] Operating expenses amounts allocated to Research and development, Sales, marketing and services, and General and administrative are not individually significant.