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Period which an employee's right to exercise an award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Share-based compensation - Additional Information (Detail) $ / shares in Units, $ in Thousands					1 Months Ended		3 Months Ended	9 Months Ended	12 Months Ended
	Mar. 12, 2018 USD ($) shares	Dec. 08, 2015 shares	Nov. 16, 2015 shares	Nov. 16, 2015 USD ($) shares	Jan. 31, 2018 shares	Dec. 31, 2017 shares	Mar. 31, 2018 USD ($) shares	Sep. 30, 2018 shares	Dec. 31, 2018 USD ($) plan $ / shares shares	Dec. 31, 2017 USD ($) shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense \| $									$ 14,681	$ 31,125
Closing stock market price (in dollars per share) \| $ / shares									$ 3.6
Compensation cost recognized \| $									$ 30,393	33,996
Unrecognized share-based compensation cost in respect of granted share options \| $									7,418
General and Administrative Expenses
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation cost recognized \| $									5,739	28,448
Michael Brauser, Chairman of the Board
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Annual base salary \| $				$ 25
Number of shares accelerated and related to share-based compensation expense (in shares)							2,500,000
Share-based compensation expense \| $									302	1,742
Compensation cost recognized \| $							$ 6,468
Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock units, compensation cost \| $									$ 15,104	$ 35,169
Unrecognized share-based compensation weighted average period									1 year 10 months 24 days
Restricted Stock Units \| Michael Brauser, Chairman of the Board
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted share units, issued (in shares)					1,250,000	1,250,000
Number of shares accelerated and related to share-based compensation expense (in shares)	2,500,000
Accelerated share-based compensation expense \| $							$ 6,468
Restricted Stock Units \| Stockholder Approval \| Michael Brauser, Chairman of the Board
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares issuable upon exercise of restricted stock unit (in shares)			5,000,000	5,000,000
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of restricted stock units outstanding (in shares)									150,000
Employee Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares accelerated and related to share-based compensation expense (in shares)								47,500
Number of share options, exercised (in shares)										0
Fair value of option vested \| $									$ 159	$ 125
Compensation cost recognized \| $									$ 243	$ 123
Marlin Capital Investments, LLC \| Michael Brauser Managing
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Ownership percentage by Mike Brauser in Marlin Capital Investments LLC									50.00%
Marlin Capital Investments, LLC \| Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of restricted stock units outstanding (in shares)									2,000,000
Restricted share units, vested (in shares)	500,000
Number of shares accelerated and related to share-based compensation expense (in shares)							500,000
Accelerated share-based compensation expense \| $							$ 906
Frost Gamma \| Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted share units, issued (in shares)							3,000,000
Restricted share units, granted (in shares)		3,000,000
2015 Stock Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of share-based incentive plans \| plan									3
Number of shares of common stock authorized for issuance									21,152,558
Common stock reserved for future issuance (in shares)									156,490
2018 Stock Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for future issuance (in shares)									7,652,558
The Acceleration
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Accelerated share-based compensation expense \| $	$ 15,548
The Acceleration \| Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares accelerated and related to share-based compensation expense (in shares)	4,960,498
The Acceleration \| Restricted Stock Units \| Michael Brauser, Chairman of the Board
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares accelerated and related to share-based compensation expense (in shares)	2,500,000
The Acceleration \| Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares accelerated and related to share-based compensation expense (in shares)	150,000
The Acceleration \| Employee Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares accelerated and related to share-based compensation expense (in shares)	47,500
Spin Off Grants \| Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted share units, vested (in shares)								2,041,000
Award vesting period								3 years
Restricted share units, granted (in shares)								304,000
Spin Off Grants \| Stock Compensation Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense \| $							$ 881
Transaction Grants \| Stock Compensation Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted share units, vested (in shares)							2,041,000
Award requisite service period							3 years
Compensation cost recognized \| $							$ 5,409