Marketable Securities (Tables)

3 Months Ended

Mar. 31, 2018

Marketable Securities [Abstract]

Held-to-maturity Securities

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)	March 31, 2018		December 31, 2017		March 31, 2017
U.S. Government and agency obligations	$	15,000	$	17,910	$	12,908
Commercial paper		24,961		49,865		54,916
Total short-term marketable securities		39,961		67,775		67,824
U.S. Government and agency obligations		62,287		59,993		59,989
Corporate bonds		5,018		5,022		—
Total long-term marketable securities		67,305		65,015		59,989
Total marketable securities	$	107,266	$	132,790	$	127,813

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

(in thousands)	March 31, 2018
Due within one year	$	39,961
Due in one to five years		67,305
Total	$	107,266