Investment Securities (Continuous Unrealized Loss Position, Fair Value) (Detail) $ in Thousands	Jun. 30, 2020 USD ($)
Available-for-sale securities
Continuous unrealized losses existing for less than 12 months, fair value	$ 50,537
Continuous unrealized losses existing for less than 12 months, unrealized losses	(772)
Continuous unrealized losses existing for greater than 12 months, fair value	63,056
Continuous unrealized losses existing for greater than 12 months, unrealized losses	(4,887)
Total, fair value	113,593
Total, unrealized losses	(5,659)
U.S. Treasury
Available-for-sale securities
Continuous unrealized losses existing for less than 12 months, fair value	0
Continuous unrealized losses existing for less than 12 months, unrealized losses	0
Continuous unrealized losses existing for greater than 12 months, fair value	0
Continuous unrealized losses existing for greater than 12 months, unrealized losses	0
Total, fair value	0
Total, unrealized losses	0
U.S. Government agencies
Available-for-sale securities
Continuous unrealized losses existing for less than 12 months, fair value	0
Continuous unrealized losses existing for less than 12 months, unrealized losses	0
Continuous unrealized losses existing for greater than 12 months, fair value	0
Continuous unrealized losses existing for greater than 12 months, unrealized losses	0
Total, fair value	0
Total, unrealized losses	0
Municipal
Available-for-sale securities
Continuous unrealized losses existing for less than 12 months, fair value	42,604
Continuous unrealized losses existing for less than 12 months, unrealized losses	(238)
Continuous unrealized losses existing for greater than 12 months, fair value	944
Continuous unrealized losses existing for greater than 12 months, unrealized losses	(15)
Total, fair value	43,548
Total, unrealized losses	(253)
Corporate notes, financial issuers
Available-for-sale securities
Continuous unrealized losses existing for less than 12 months, fair value	6,469
Continuous unrealized losses existing for less than 12 months, unrealized losses	(526)
Continuous unrealized losses existing for greater than 12 months, fair value	62,112
Continuous unrealized losses existing for greater than 12 months, unrealized losses	(4,872)
Total, fair value	68,581
Total, unrealized losses	(5,398)
Corporate notes, other
Available-for-sale securities
Continuous unrealized losses existing for less than 12 months, fair value	0
Continuous unrealized losses existing for less than 12 months, unrealized losses	0
Continuous unrealized losses existing for greater than 12 months, fair value	0
Continuous unrealized losses existing for greater than 12 months, unrealized losses	0
Total, fair value	0
Total, unrealized losses	0
Mortgage-backed securities
Available-for-sale securities
Continuous unrealized losses existing for less than 12 months, fair value	1,068
Continuous unrealized losses existing for less than 12 months, unrealized losses	(7)
Continuous unrealized losses existing for greater than 12 months, fair value	0
Continuous unrealized losses existing for greater than 12 months, unrealized losses	0
Total, fair value	1,068
Total, unrealized losses	(7)
Collateralized mortgage obligations
Available-for-sale securities
Continuous unrealized losses existing for less than 12 months, fair value	396
Continuous unrealized losses existing for less than 12 months, unrealized losses	(1)
Continuous unrealized losses existing for greater than 12 months, fair value	0
Continuous unrealized losses existing for greater than 12 months, unrealized losses	0
Total, fair value	396
Total, unrealized losses	$ (1)