Benefit Plans (Narrative) (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Benefit Plans [Line Items]
Percentage of defined plan agreement	30.00%
Contributions to plan	$ 900,000	$ 900,000	$ 1,000,000
Supplemental Retirement Plans expenses	$ 200,000	$ 300,000	$ 400,000
Employee Share Purchase Plan [Member]
Benefit Plans [Line Items]
Common stock purchase at a discount	15.00%
Stock Issued During Period, Shares, Employee Stock Purchase Plans	31,000	38,000	24,000
Shares purchase consideration	$ 200,000	$ 500,000	$ 500,000
Expenses recorded to the share purchase plan	$ 43,000	$ 100,000	$ 100,000