EMPLOYEES' BENEFIT PLAN- Narratives (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plan Disclosure [Line Items]
Defined Contribution Plan, Employer Matching Contribution, Percent	25.00%
Employee contribution percent maximum to get employer matching contribution	4.00%
Total plan expense	$ 900,000	$ 1,100,000	$ 1,400,000
P R
Defined Benefit Plan Disclosure [Line Items]
Defined Contribution Plan, Maximum Annual Contribution Per Employee, Amount	15,000	15,000	15,000
United States And Virign Islands Operations [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Contribution Plan, Maximum Annual Contribution Per Employee, Amount	$ 18,000	$ 18,000	$ 18,000