Marketable Securities (Tables)

6 Months Ended

Jun. 30, 2018

All marketable securities were classified as held-to-maturity as of the dates presented and the carrying amounts of held-to-maturity securities were as follows:

(in thousands)	June 30, 2018		December 31, 2017		June 30, 2017
U.S. Government and agency obligations	$	15,000	$	17,910	$	12,909
Commercial paper		—		49,865		34,912
Corporate bonds		5,014		—		—
Total short-term marketable securities		20,014		67,775		47,821
U.S. Government and agency obligations		61,191		59,993		59,990
Corporate bonds		—		5,022		—
Total long-term marketable securities		61,191		65,015		59,990
Total marketable securities	$	81,205	$	132,790	$	107,811

Scheduled maturities of held-to-maturity investments were as follows:

(in thousands)	June 30, 2018
Due within one year	$	20,014
Due in one to five years		61,191
Total	$	81,205