Leases - Schedule of Lease Expense, Cash Flow, Operating and Finance Lease Assets and Liabilities, Average Lease Term and Average Discount Rate (Parenthetical) (Detail) - USD ($) $ in Thousands	Jun. 30, 2019	Jan. 01, 2019
Lessee Lease Description [Line Items]
Operating lease, right-of-use asset	$ 16,903
Accounting Standards Update 2016-02 [Member]
Lessee Lease Description [Line Items]
Operating lease, right-of-use asset		$ 18,200