Stock-Based Compensation - Summary of Restricted Stock Units Awarded Under Equity Plan (Detail) - $ / shares	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Time-vesting RSUs [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Awards, Nonvested, Beginning Balance	422,059
Number of Awards, granted	310,700	135,759	276,085
Number of Awards, vested	(174,774)
Number of Awards, forfeited	(24,382)
Number of Awards, Nonvested, Ending Balance	533,603	422,059
Weighted-Average Grant Date Fair Value Per Share, Nonvested, Beginning Balance	$ 16.57
Weighted-Average Grant Date Fair Value Per Share, granted	10.47
Weighted-Average Grant Date Fair Value Per Share, vested	18.20
Weighted-Average Grant Date Fair Value Per Share, forfeited	13.42
Weighted-Average Grant Date Fair Value Per Share, Nonvested, Ending Balance	$ 12.58	$ 16.57
Performance-Vesting RSUs [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Awards, Nonvested, Beginning Balance	741,973
Number of Awards, granted	190,634	194,563	370,616
Number of Awards, vested	(223,330)
Number of Awards, Nonvested, Ending Balance	709,277	741,973
Weighted-Average Grant Date Fair Value Per Share, Nonvested, Beginning Balance	$ 17.53
Weighted-Average Grant Date Fair Value Per Share, granted	10.49
Weighted-Average Grant Date Fair Value Per Share, vested	21.44
Weighted-Average Grant Date Fair Value Per Share, Nonvested, Ending Balance	$ 14.41	$ 17.53

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

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-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=116856206&loc=d3e5070-113901

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- Definition

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.

+ References

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-Publisher FASB
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-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
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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).

+ References

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-Publisher FASB
-Name Accounting Standards Codification
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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).

+ References

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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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Per share or unit weighted-average fair value of nonvested award under share-based payment arrangement. Excludes share and unit options.

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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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The weighted average fair value as of grant date pertaining to an equity-based award plan other than a stock (or unit) option plan for which the grantee gained the right during the reporting period, by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash in accordance with the terms of the arrangement.

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- Definition

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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