Leases - Additional Information (Detail) - USD ($) $ in Thousands			12 Months Ended
	Aug. 16, 2016	Jun. 02, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Jun. 30, 2017
Leases Disclosure [Line Items]
Gross proceeds from sale and leaseback agreement				$ 14,244
Sublease agreement period		5 years
Weighted average effective interest rate of initial sale leaseback financing liability			2.22%
Lease agreement term			In June 2017, the Company amended the lease agreement. The amendment extended the lease through June of 2031 and changed the effective weighted average interest rate from the 2.22% to the 4.53%.
Amended lease agreement term			2017-06
Amendment extended lease term			2031-06
Weighted average effective interest rate of sale leaseback financing liability		2.22%				4.53%
Gain on sale of facility	$ 2,000	$ 2,400
Capital lease obligations	$ 3,000	$ 5,700
Capital lease weighted average interest rate	3.25%	3.43%
Rent expense			$ 4,200	4,500	$ 4,000
Denton, Texas Facility [Member]
Leases Disclosure [Line Items]
Gross proceeds from sale and leaseback agreement		$ 5,000
Sale leaseback transaction costs		300
Net proceeds from sale and leaseback agreement		$ 4,700
Initial lease agreement period		13 years
Sale leaseback transaction, net carrying value			$ 11,000	$ 12,300
Telford, Pennsylvania Facility [Member]
Leases Disclosure [Line Items]
Gross proceeds from sale and leaseback agreement		$ 6,000
Sale leaseback transaction costs		400
Net proceeds from sale and leaseback agreement		$ 5,600
Lease agreement period		13 years
Indianapolis, Indiana Facility [Member]
Leases Disclosure [Line Items]
Gross proceeds from sale and leaseback agreement	$ 3,300
Sale leaseback transaction costs	100
Net proceeds from sale and leaseback agreement	$ 3,200
Lease agreement period	13 years