Comprehensive Income (Reclassifications out of Accumulated Other Comprehensive Loss) (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2018	Mar. 31, 2017
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Unrealized net losses on available-for-sale securities		$ 3,012	$ (3,326)
Unrealized net gains on cash flow hedges		423,343	437,575
Net income		(144,259)	$ (27,621)
Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net income		(218)
Unrealized Gain 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 losses on available-for-sale securities		1,001
Unrealized Gain on Derivative Instruments [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Unrealized net gains on cash flow hedges	[1]	$ (1,219)

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