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Income Taxes - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Income Tax [Line Items]
Statutory income tax rates	21.00%	35.00%
Effective income tax benefit rate	(28.20%)	(32.30%)
Adjustments to provisional tax estimates	$ 0
Alternative minimum tax credit carry forward			$ 11,000
Net operating loss carryforwards	14,700		16,300
AMT credit carryforward reclassed to federal income tax receivable	10,157		10,332
Section 163(j) carryforward	$ 7,900		7,900
Alternative Minimum Tax Credits
Income Tax [Line Items]
AMT credit carryforward reclassed to federal income tax receivable			$ 11,000
UNITED STATES
Income Tax [Line Items]
Statutory income tax rates	21.00%
BERMUDA
Income Tax [Line Items]
Statutory income tax rates	0.00%
CAYMAN ISLANDS
Income Tax [Line Items]
Statutory income tax rates	0.00%
LUXEMBOURG
Income Tax [Line Items]
Statutory income tax rates	26.01%
IRELAND | Non Trading Income
Income Tax [Line Items]
Statutory income tax rates	25.00%
IRELAND | Capital Gain
Income Tax [Line Items]
Statutory income tax rates	33.00%
IRELAND | Trading Income
Income Tax [Line Items]
Statutory income tax rates	12.50%
BARBADOS | Minimum
Income Tax [Line Items]
Statutory income tax rates	0.25%
BARBADOS | Maximum
Income Tax [Line Items]
Statutory income tax rates	2.50%

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The foreign statutory tax rate applicable under enacted tax laws to the Company's pretax income from continuing operations for the period.

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Tax Cuts and Jobs Act of 2017, change in tax rate, income tax expense (benefit).

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible operating loss carryforwards that are not subject to expiration dates.

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible alternative minimum tax credit carryforwards.

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Percentage of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

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Percentage of domestic federal statutory tax rate applicable to pretax income (loss).

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Carrying amount as of the balance sheet date of income taxes previously overpaid to tax authorities (such as U.S. Federal, state and local tax authorities) representing refunds of overpayments or recoveries based on agreed-upon resolutions of disputes. Also called income tax refund receivable.

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Amount of operating loss carryforward, before tax effects, available to reduce future taxable income under enacted tax laws.

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