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Marketable Securities - Available-for-sale Marketable Securities in Gross Unrealized Loss Position (Details)
Mar. 31, 2021
USD ($)
Marketable Securities [Line Items]  
Estimated fair value, less than 12 months
Gross unrealized holding losses, less than 12 months
Estimated fair value, more than 12 months
Gross unrealized holding losses, more than 12 months
Estimated fair value
Gross unrealized holding losses
Corporate bonds and notes [Member]  
Marketable Securities [Line Items]  
Estimated fair value, less than 12 months
Gross unrealized holding losses, less than 12 months
Estimated fair value, more than 12 months
Gross unrealized holding losses, more than 12 months
Estimated fair value
Gross unrealized holding losses
Municipal bonds [Member]  
Marketable Securities [Line Items]  
Estimated fair value, less than 12 months
Gross unrealized holding losses, less than 12 months
Estimated fair value, more than 12 months
Gross unrealized holding losses, more than 12 months
Estimated fair value
Gross unrealized holding losses