| Summary of Marketable Securities | 
The amortized cost and fair value of marketable securities as of the dates indicated below were as follows: 
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As of September 30, 2016 (In thousands)  | 
 Amortized 
Cost 
 | 
   | 
 Gross 
Unrealized 
Gains 
 | 
   | 
 Gross 
Unrealized 
Losses 
 | 
   | 
 Fair 
Value 
 | 
 
U.S. Treasury securities  | 
$  | 
271,546  | 
 
  | 
   | 
$  | 
514  | 
 
  | 
   | 
$  | 
(92  | 
)  | 
   | 
$  | 
271,968  | 
 
  | 
 
U.S. Government agency securities  | 
423,741  | 
 
  | 
   | 
426  | 
 
  | 
   | 
(149  | 
)  | 
   | 
424,018  | 
 
  | 
 
Municipal securities  | 
3,008  | 
 
  | 
   | 
1  | 
 
  | 
   | 
—  | 
 
  | 
   | 
3,009  | 
 
  | 
 
Corporate debt securities  | 
840,857  | 
 
  | 
   | 
1,067  | 
 
  | 
   | 
(599  | 
)  | 
   | 
841,325  | 
 
  | 
 
Money market and other  | 
581,240  | 
 
  | 
   | 
—  | 
 
  | 
   | 
—  | 
 
  | 
   | 
581,240  | 
 
  | 
 
Sovereign securities  | 
21,972  | 
 
  | 
   | 
3  | 
 
  | 
   | 
(4  | 
)  | 
   | 
21,971  | 
 
  | 
 
Subtotal  | 
2,142,364  | 
 
  | 
   | 
2,011  | 
 
  | 
   | 
(844  | 
)  | 
   | 
2,143,531  | 
 
  | 
 
Add: Time deposits(1)
  | 
30,546  | 
 
  | 
   | 
—  | 
 
  | 
   | 
—  | 
 
  | 
   | 
30,546  | 
 
  | 
 
Less: Cash equivalents  | 
645,783  | 
 
  | 
   | 
—  | 
 
  | 
   | 
(2  | 
)  | 
   | 
645,781  | 
 
  | 
 
Marketable securities  | 
$  | 
1,527,127  | 
 
  | 
   | 
$  | 
2,011  | 
 
  | 
   | 
$  | 
(842  | 
)  | 
   | 
$  | 
1,528,296  | 
 
  | 
 
  
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As of June 30, 2016 (In thousands)  | 
Amortized Cost  | 
   | 
Gross Unrealized Gains  | 
   | 
Gross Unrealized Losses  | 
   | 
Fair Value  | 
 
U.S. Treasury securities  | 
$  | 
326,321  | 
 
  | 
   | 
$  | 
1,181  | 
 
  | 
   | 
$  | 
—  | 
 
  | 
   | 
$  | 
327,502  | 
 
  | 
 
U.S. Government agency securities  | 
404,889  | 
 
  | 
   | 
830  | 
 
  | 
   | 
(14  | 
)  | 
   | 
405,705  | 
 
  | 
 
Municipal securities  | 
5,014  | 
 
  | 
   | 
2  | 
 
  | 
   | 
—  | 
 
  | 
   | 
5,016  | 
 
  | 
 
Corporate debt securities  | 
676,259  | 
 
  | 
   | 
2,372  | 
 
  | 
   | 
(157  | 
)  | 
   | 
678,474  | 
 
  | 
 
Money market and other  | 
626,156  | 
 
  | 
   | 
—  | 
 
  | 
   | 
—  | 
 
  | 
   | 
626,156  | 
 
  | 
 
Sovereign securities  | 
41,224  | 
 
  | 
   | 
38  | 
 
  | 
   | 
(5  | 
)  | 
   | 
41,257  | 
 
  | 
 
Subtotal  | 
2,079,863  | 
 
  | 
   | 
4,423  | 
 
  | 
   | 
(176  | 
)  | 
   | 
2,084,110  | 
 
  | 
 
Add: Time deposits(1)
  | 
77,131  | 
 
  | 
   | 
—  | 
 
  | 
   | 
—  | 
 
  | 
   | 
77,131  | 
 
  | 
 
Less: Cash equivalents  | 
778,451  | 
 
  | 
   | 
1  | 
 
  | 
   | 
(17  | 
)  | 
   | 
778,435  | 
 
  | 
 
Marketable securities  | 
$  | 
1,378,543  | 
 
  | 
   | 
$  | 
4,422  | 
 
  | 
   | 
$  | 
(159  | 
)  | 
   | 
$  | 
1,382,806  | 
 
  | 
 
  
________________ 
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(1)   | 
Time deposits excluded from fair value measurements.  | 
 
 
 
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| Investments with Gross Unrealized Losses | 
The following table summarizes the fair value and gross unrealized losses of the Company’s investments that were in an unrealized loss position as of the date indicated below: 
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As of September 30, 2016 (In thousands)  | 
Fair Value  | 
   | 
 Gross  
Unrealized  
Losses(1)
 
 | 
 
Corporate debt securities  | 
$  | 
372,827  | 
 
  | 
   | 
$  | 
(597  | 
)  | 
 
U.S. Government agency securities  | 
126,547  | 
 
  | 
   | 
(149  | 
)  | 
 
U.S. Treasury securities  | 
44,791  | 
 
  | 
   | 
(92  | 
)  | 
 
Sovereign securities  | 
13,036  | 
 
  | 
   | 
(4  | 
)  | 
 
Municipal securities  | 
2,006  | 
 
  | 
   | 
—  | 
 
  | 
 
Total  | 
$  | 
559,207  | 
 
  | 
   | 
$  | 
(842  | 
)  | 
 
  
 
__________________  
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(1)  | 
As of September 30, 2016, the amount of total gross unrealized losses related to investments that had been in a continuous loss position for 12 months or more was immaterial.
  | 
 
 
 
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| Contractual Maturities of Securities | 
The contractual maturities of securities classified as available-for-sale, regardless of their classification on the Company’s Condensed Consolidated Balance Sheet, as of the date indicated below were as follows: 
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As of September 30, 2016 (In thousands)  | 
Amortized Cost  | 
   | 
Fair Value  | 
 
Due within one year  | 
$  | 
531,572  | 
 
  | 
   | 
$  | 
531,730  | 
 
  | 
 
Due after one year through three years  | 
995,555  | 
 
  | 
   | 
996,566  | 
 
  | 
 
   | 
$  | 
1,527,127  | 
 
  | 
   | 
$  | 
1,528,296  | 
 
  | 
 
  
 
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