Leases (Supplemental Balance Sheet Information) (Detail) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Leases [Abstract]
Operating lease right-of-use assets	$ 40,960	$ 41,142
Operating lease liabilities	$ 42,323	$ 42,042
Operating lease, right-of-use asset, statement of financial position [Extensible List]	Other assets	Other assets
Operating lease, liability, statement of financial position [Extensible List]	Other liabilities	Other liabilities