Represents the expense recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees.

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Face amount or stated value per share of common stock.

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Weighted average period over which unrecognized compensation is expected to be recognized for equity-based compensation plans, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Unrecognized cost of unvested options awarded to employees as compensation.

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Estimated period over which an employee is required to provide service in exchange for the equity-based payment award, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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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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The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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Fair value of share-based awards for which the grantee gained the right by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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No definition available.

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Percentage of vesting of share-based compensation awards.

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Stock-Based Compensation and Other Benefit Plans - Additional Information (Detail) - USD ($)				3 Months Ended		12 Months Ended
	Mar. 21, 2018	Feb. 21, 2018	Feb. 07, 2017	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2017
2009 Stock Option Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation cost related to shares awards				$ 0
2013 Stock Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation cost related to shares awards				5,000
Weighted-average life over which expense is expected to be recognized (years)						2 months
2016 Stock Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation cost related to shares awards				$ 4,500,000
Weighted-average life over which expense is expected to be recognized (years)				3 years 5 months 1 day
Restricted Shares \| 2016 Stock Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted-average life over which expense is expected to be recognized (years)				1 year 1 month 6 days	1 year 9 months 4 days
Awards granted (in shares)				0
Share-based compensation expense				$ 649,000	$ 376,000
Restricted Stock Units (RSUs) \| 2016 Stock Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted-average life over which expense is expected to be recognized (years)				4 years 3 months 18 days	9 months 4 days
Awards granted (in shares)				60,635
Share-based compensation expense				$ 496,000	$ 277,000
Employee Restricted Stock Units \| 2016 Stock Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awards granted (in shares)				41,620
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period				5 years
Award fair value				$ 2,300,000
Performance Restricted Stock Unit Awards \| 2016 Stock Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted-average life over which expense is expected to be recognized (years)				2 years 5 months 5 days	2 years 9 months
Awards granted (in shares)				84,836
Share-based compensation expense				$ 364,000	$ 14,000
Cash phantom units (CPUs) \| Long-Term Incentive Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
CPU, par value (in dollars per share)	$ 0.001
Award fair value	$ 1,000,000
Share-based Compensation Arrangement by Share-based Payment Award, Award Requisite Service Period	3 years
Share-based compensation expense				$ 11,000
Class A Common Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
CPU, par value (in dollars per share)				$ 0.001			$ 0.001
Directors \| Restricted Stock Units (RSUs) \| 2016 Stock Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awards granted (in shares)		19,015
Award fair value		$ 1,100,000
Executive \| Restricted Stock Units (RSUs) \| 2016 Stock Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award fair value	$ 4,800,000
Vest on March 30, 2017 \| Directors \| Restricted Stock Units (RSUs) \| 2016 Stock Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting rights percentage		25.00%
Vest on June 30, 2017 \| Directors \| Restricted Stock Units (RSUs) \| 2016 Stock Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting rights percentage		25.00%
Vest on September 30, 2017 \| Directors \| Restricted Stock Units (RSUs) \| 2016 Stock Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting rights percentage			25.00%
Vest on December 31, 2017 \| Directors \| Restricted Stock Units (RSUs) \| 2016 Stock Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting rights percentage			25.00%
Minimum \| Performance Restricted Stock Unit Awards \| 2016 Stock Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting rights percentage				0.00%
Minimum \| Cash phantom units (CPUs) \| Long-Term Incentive Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awards granted (in shares)	18,050
Minimum \| Executive \| Restricted Stock Units (RSUs) \| 2016 Stock Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awards granted (in shares)	84,836
Maximum \| Performance Restricted Stock Unit Awards \| 2016 Stock Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting rights percentage				125.00%
Maximum \| Cash phantom units (CPUs) \| Long-Term Incentive Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awards granted (in shares)	22,562
Award fair value	$ 1,300,000
Maximum \| Executive \| Restricted Stock Units (RSUs) \| 2016 Stock Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awards granted (in shares)	106,043
Award fair value	$ 5,900,000