Fair Value Measurements - Schedule of Available for Sale Securities Maturities (Details) $ in Millions	Mar. 31, 2019 USD ($)
Cost Basis
Due within one year	$ 4,613
Due after one year through five years	60
Due after five years through ten years	0
Total debt securities	4,673
Fair Value
Due within one year	4,613
Due after one year through five years	60
Due after five years through ten years	0
Total debt securities	$ 4,673

Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), with single maturity date and allocated without single maturity date, maturing in sixth fiscal year through tenth fiscal year following latest fiscal year. Excludes interim and annual periods when interim period is reported on rolling approach, from latest statement of financial position date.

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Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), with single maturity date and allocated without single maturity date, maturing in second through fifth fiscal year following latest fiscal year. Excludes interim and annual periods when interim period is reported on rolling approach, from latest statement of financial position date.

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