Share Based Compensation (Schedule of Changes in Number of Options Outstanding) (Detail) - 2003 Equity Incentive Plan [Member] - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options forfeited	0	0	(5,000)
Options outstanding at December 31	10,000	10,000	10,000	15,000
Outstanding exercisable options at December 31, 2013 Options	10,000
Average exercise price per share	$ 16.63
Aggregate exercise price	$ 166
Intrinsic value of options outstanding	$ 0