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Short-Term Investments (Tables)

9 Months Ended

Sep. 30, 2019

Short Term Investments [Abstract]

Summary of Short-Term Investments

The following is a summary of our short-term investments (in thousands):

		September 30, 2019
						Gross				Gross
		Amortized				Unrealized				Unrealized				Estimated
		Cost				Gains				Losses				Fair Value
U.S. treasury bills and government agency obligations		$	69,702			$	57			$	—			$	69,759
U.S. corporate debt securities			29,078				23				—				29,101
Foreign corporate debt securities			10,670				18				—				10,688
U.S. commercial paper			32,363				5				—				32,368
Foreign commercial paper			54,254				—				—				54,254
Total		$	196,067			$	103			$	—			$	196,170

		December 31, 2018
						Gross				Gross
		Amortized				Unrealized				Unrealized				Estimated
		Cost				Gains				Losses				Fair Value
U.S. treasury bills and government agency obligations		$	59,747			$	—			$	(6	)		$	59,741
U.S. corporate debt securities			59,164				—				(77	)			59,087
Foreign corporate debt securities			5,041				5				—				5,046
U.S. commercial paper			52,800				—				—				52,800
Foreign commercial paper			123,870				—				(9	)			123,861
Total		$	300,622			$	5			$	(92	)		$	300,535