Income Taxes - Schedule of Effective Income Tax Rate Reconciliation (Detail)	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Income tax at the federal statutory rate	35.00%	35.00%	35.00%
Dividends on preferred securities	80.70%	3.40%	(8.00%)
True-up of deferred assets	13.70%	(0.50%)
Adjustments to NOL due to change in tax rate	10766.60%
Adjustments to capital loss carryforward due to expiration	662.90%
Stock Based Compensation	(13.70%)
Change in valuation allowance	(11545.20%)	(37.90%)	(27.00%)
Effective rate	0.00%	0.00%	0.00%

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

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 13
-URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32698-109319

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

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Percentage of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to changes in the valuation allowance for deferred tax assets.

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-Publisher FASB
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Effective income tax rate reconciliation expiration of capital loss carryforward.

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Effective income tax true up of deferred assets.

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