Commitments and Contingencies (Tables)

12 Months Ended

Dec. 31, 2017

Commitments and Contingencies Disclosure [Abstract]

Future Minimum Rental Commitments Under Operating Leases

Future minimum rental commitments under non-cancelable leases as of December 31, 2017 (excluding commitments for the Clopper Road Lease as described below as this lease was terminated in January 2018) are as follows (in thousands):

Year	Operating Leases
2018	$	6,695
2019		6,693
2020		5,416
2021		5,398
2022		5,515
Thereafter		6,801
Total minimum lease payments	$	36,518