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Stockholders' Equity - Summary of Restricted Stock, Restricted Stock Unit and Performance-based Stock Unit Activity (Detail) $ / shares in Units, shares in Thousands, $ in Thousands	6 Months Ended
	Jun. 30, 2016 USD ($) $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted Average Grant Price, Outstanding, December 31, 2015 | $ / shares	$ 4.49
Weighted Average Grant Price, Granted | $ / shares	6.32
Weighted Average Grant Price, Forfeited | $ / shares	5.07
Weighted Average Grant Price, Outstanding, June 30, 2016 | $ / shares	5.29
Weighted Average Grant Price, Expected to vest, June 30, 2016 | $ / shares	$ 5.25
Weighted Average Remaining Contractual Term, Outstanding	2 years
Weighted Average Remaining Contractual Term, Expected to vest	2 years
Aggregate Intrinsic Value, Outstanding, June 30, 2016 | $	$ 2,452
Aggregate Intrinsic Value,Expected to vest, June 30, 2016 | $	$ 2,082
Restricted Stock, Restricted Stock Units and Performance-Based Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted Stock, Restricted Stock Units, and Performance-Based Stock Units Outstanding, December 31, 2015 | shares	962
Restricted Stock, Restricted Stock Units, and Performance-Based Stock Units, Granted | shares	400
Restricted Stock, Restricted Stock Units, and Performance-Based Stock Units, Forfeited | shares	(5)
Restricted Stock, Restricted Stock Units, and Performance-Based Stock Units Outstanding, December 31, 2015 | shares	959
Restricted Stock, Restricted Stock Units, and Performance-Based Stock Units Expected to vest, December 31, 2015 | shares	799
Class A Common Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted Average Grant Price Common Stock, Vested | $ / shares	$ 4.38
Class A Common Stock [Member] | Restricted Stock, Restricted Stock Units and Performance-Based Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted Stock, Restricted Stock Units, and Performance-Based Stock Units Common Stock, Vested | shares	(398)

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Intrinsic value of equity-based awards excluding options expected to vest.

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The number of equity-based awards other than stock options that are expected to vest.

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The number of equity-based payment instruments, excluding stock (or unit) options, that were forfeited during the reporting period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(iv)(3)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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Weighted average fair value as of the grant date of equity-based award plans other than stock (unit) option plans that were not exercised or put into effect as a result of the occurrence of a terminating event.

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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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The weighted average fair value at grant date for nonvested equity-based awards issued 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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The number of non-vested equity-based payment instruments, excluding stock (or unit) options, that validly exist and are outstanding as of the balance sheet date.

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-Publisher FASB
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The number of equity-based payment instruments, excluding stock (or unit) options, that vested during the reporting period.

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Intrinsic value of equity-based compensation awards outstanding. Excludes stock and unit options.

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