Fair Value of Each Award Estimated on Date of Grant Using Black-Scholes-Merton Option-Pricing Formula (Detail) - $ / shares	12 Months Ended
Dec. 31, 2017	Dec. 31, 2015
Performance Restricted Stock Units [Domain]
Schedule of Benefit Obligations Weighted Average Assumptions [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value	$ 57.81
Predecessor [Member] \| Stock Options
Schedule of Benefit Obligations Weighted Average Assumptions [Line Items]
Expected volatility, min		64.60%
Expected volatility, max		69.40%
Dividend yield, min		0.00%
Dividend yield, max		0.00%
Risk-free interest rate, min		0.87%
Risk-free interest rate, max		1.54%
Predecessor [Member] \| Stock Options \| Minimum
Schedule of Benefit Obligations Weighted Average Assumptions [Line Items]
Expected life		3 years 6 months
Predecessor [Member] \| Stock Options \| Maximum
Schedule of Benefit Obligations Weighted Average Assumptions [Line Items]
Expected life		4 years 7 months
Predecessor [Member] \| Performance Based Restricted Stock Units (PBRSUs)
Schedule of Benefit Obligations Weighted Average Assumptions [Line Items]
Expected volatility, min		66.50%
Expected volatility, max		97.70%
Dividend yield, min		0.00%
Dividend yield, max		0.00%
Risk-free interest rate, min		1.00%
Risk-free interest rate, max		1.31%
Successor [Member] \| Performance Restricted Stock Units [Domain]
Schedule of Benefit Obligations Weighted Average Assumptions [Line Items]
Expected volatility, min	59.63%
Expected volatility, max	62.18%
Dividend yield, min	0.00%
Dividend yield, max	0.00%
Risk-free interest rate, min	1.44%
Risk-free interest rate, max	1.51%
Share-based Compensation Award, Tranche One [Member] \| Successor [Member] \| Performance Restricted Stock Units [Domain] \| Minimum
Schedule of Benefit Obligations Weighted Average Assumptions [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value	$ 47.70
Share-based Compensation Award, Tranche One [Member] \| Successor [Member] \| Performance Restricted Stock Units [Domain] \| Maximum
Schedule of Benefit Obligations Weighted Average Assumptions [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value	$ 65.28

Schedule of Benefit Obligations Weighted Average Assumptions [Line Items]

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Share Based Compensation Arrangement by Share Based Payment Award, Fair Value Assumptions, Expected Dividend Rate, Maximum

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No definition available.

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- Definition

Share Based Compensation Arrangement by Share Based Payment Award, Fair Value Assumptions, Expected Dividend Rate Minimum

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- Definition

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 estimated measure of the maximum percentage by which a share price is expected to fluctuate during a period. Volatility also may be defined as a probability-weighted measure of the dispersion of returns about the mean. The volatility of a share price is the standard deviation of the continuously compounded rates of return on the share over a specified period. That is the same as the standard deviation of the differences in the natural logarithms of the stock prices plus dividends, if any, over the period.

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The estimated measure of the minimum percentage by which a share price is expected to fluctuate during a period. Volatility also may be defined as a probability-weighted measure of the dispersion of returns about the mean. The volatility of a share price is the standard deviation of the continuously compounded rates of return on the share over a specified period. That is the same as the standard deviation of the differences in the natural logarithms of the stock prices plus dividends, if any, over the period.

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The maximum risk-free interest rate assumption that is used in valuing an option on its own shares.

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The minimum risk-free interest rate assumption that is used in valuing an option on its own shares.

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- Definition

Expected term of share-based compensation awards, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ 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 (f)(2)(i)
-URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SAB Topic 14.D.2)
-URI http://asc.fasb.org/extlink&oid=27013229&loc=d3e301413-122809

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