Investment Securities (Other Than Temporary Impairment Credit Losses Recognized In Earnings) (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Roll Forward]
Beginning Balance OTTI	$ 822	$ 1,364	$ 822	$ 1,364
Other than Temporary Impairment, Credit Losses Recognized in Earnings, Reductions, Securities Sold	0	(261)	0	(261)
Other than Temporary Impairment, Credit Losses Recognized in Earnings, Credit Losses on Debt Securities Held	$ 822	$ 1,364	$ 822	$ 1,364	$ 822	$ 1,103