XML 48 R20.htm IDEA: XBRL DOCUMENT

Fair Value Measurements Fair Value Measurements (Tables)

6 Months Ended

Jun. 30, 2019

Fair Value Disclosures [Abstract]

Fair Value, Assets Measured on Recurring and Nonrecurring Basis [Table Text Block]

The following table summarizes the levels of fair value measurements of our financial assets:



	June 30, 2019										December 31, 2018
(in thousands)	Total			Level 1			Level 2				Total			Level 1			Level 2

Money market funds	$	303,908		$	303,908		$	—			$	325,819		$	325,819		$	—
U.S. Treasury bills	59,775			59,775			—				52,197			52,197			—
Municipal bonds	3,425			—			3,425				10,634			—			10,634
Total	$	367,108		$	363,683		$	3,425			$	388,650		$	378,016		$	10,634

Available-for-sale Securities [Table Text Block]

The following is a summary of our available-for-sale marketable securities:



(in thousands)	Amortized Cost			Gross Unrealized Gains			Gross Unrealized Losses			Estimated Fair Value

June 30, 2019
U.S. Treasury bills	$	57,650		$	54		$	—		$	57,704
Municipal bonds	3,425			—			—			3,425
Total	$	61,075		$	54		$	—		$	61,129

December 31, 2018
U.S. Treasury bills	$	50,150		$	—		$	(3	)	$	50,147
Municipal bonds	10,640			1			(7		)	10,634
Total	$	60,790		$	1		$	(10	)	$	60,781

Investments Classified by Contractual Maturity Date [Table Text Block]

As of June 30, 2019, the contractual maturities of our marketable securities were as follows:



(in thousands)	Amortized Cost			Estimated Fair Value

Less than one year	$	61,075		$	61,129
One to five years	—			—
Total	$	61,075		$	61,129