Financial Instruments (Details 2) $ in Thousands	Jun. 30, 2018 USD ($)
Amortized Cost
Due in one year or less	$ 1,758,865
Due after one year through five years	176,391
Due after five years through ten years	148,349
Due after ten years	785,984
Amortized Cost Total	2,869,589
Estimated Fair Value
Due in one year or less	1,758,593
Due after one year through five years	172,941
Due after five years through ten years	143,894
Due after ten years	764,086
Estimated Fair Value Total	2,839,514
Marketable debt securities with contractual maturities greater than one year but classified as short-term investment	$ 1,080,000