Lease Obligations - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Jan. 01, 2019
Lessee Lease Description [Line Items]
Operating lease liabilities	$ 3,349
Operating lease, right-of-use asset	$ 3,399
Sales-type lease, lease not yet commenced description	There were no sales and leaseback transactions, leverage leases, lease transactions with related parties or leases that had not yet commenced during the three months ended March 31, 2019.
ASU 2016-02 [Member]
Lessee Lease Description [Line Items]
Operating lease liabilities			$ 3,251
Operating lease, right-of-use asset			$ 3,251
Operating lease, rent expense		$ 165