Fair Value Measurements (Foreclosed Assets Remeasured and Reported at Fair Value) (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Foreclosed Assets Remeasured at Initial Recognition Carrying Value Of Foreclosed Assets Prior To Remeasurement	$ 2,899	$ 279	$ 756
Foreclosed Assets Remeasured at Initial Recognition Charge Offs Recognized In Allowance For Loan Losses	0	0	(3)
Fair Value of Foreclosed Assets Remeasured at Initial Recognition	2,899	279	753
Foreclosed Assets Remeasured Subsequent to Initial Recognition Carrying Value Of Foreclosed Assets Prior To Remeasurement	1,823	89	492
Foreclosed Assets Remeasured Subsequent to initial Recognition Write Downs Included In Other Non Interest Expense	(473)	(16)	(217)
Fair Value of Foreclosed Assets remeasured subsequent to initial recognition	$ 1,350	$ 73	$ 275