Summary of Significant Accounting Policies - ROU assets and lease liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2019	Jan. 01, 2019
Operating Lease, Liability [Abstract]
Right-of-use assets - operating leases	$ 24,026	$ 70,892
Lease liabilities - operating leases	$ 17,957	$ 40,921