Lease Exit and Related Charges (Changes to Accrued Loss on Excess Office Facilities) (Detail) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2019	Mar. 31, 2018
Loans and Leases Receivable Disclosure [Line Items]
Lease exit and related charges (benefit)	$ 0	$ 325

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Period Type:	duration