Financial Instruments (Tables)

12 Months Ended

Dec. 31, 2019

Financial Instruments

Schedule of available-for-sale securities


		December 31, 2019												December 31, 2018
		Amortized Cost			Gross Unrealized Gain			Gross Unrealized (Loss)			Estimated Fair Value			Amortized Cost			Gross Unrealized Gain			Gross Unrealized (Loss)			Estimated Fair Value
		(in thousands)
Money market deposits		$	22,477		$	—		$	—		$	22,477		$	26,539		$	—		$	—		$	26,539
U.S. Treasury securities			292,506			731			(80)			293,157			76,061			29			(405)			75,685
U.S. agency securities			—			—			—			—			13,017			—			(126)			12,891
Municipal securities			85,638			277			(7)			85,908			18,935			7			(57)			18,885
Total		$	400,621		$	1,008		$	(87)		$	401,542		$	134,552		$	36		$	(588)		$	134,000

Classified as:
Cash equivalents											$	22,477											$	26,539
Short-term investments												379,065												107,461
Total											$	401,542											$	134,000

Change in net unrealized positions of available-for-sale securities and reclassifications from AOCL upon sale


		December 31,
		2019			2018
		(in thousands)
Balance at beginning of year		$	(552)		$	(766)
Net unrealized gains (losses) on available-for-sale securities, net of tax			1,487			171
Reclassifications of losses (gains) realized from sale of available-for-sale securities			(16)			43
Increase (decrease) in other comprehensive loss			1,471			214
Balance at end of year		$	919		$	(552)

Summarized portfolio of available-for-sale securities by contractual maturity


		December 31, 2019
		Amortized Cost			Fair Value
		(in thousands)
Less than one year		$	141,380		$	141,552
Greater than one year but less than five years			236,764			237,513
Total		$	378,144		$	379,065