Assets and Liabilities Measured at Fair Value on a Recurring Basis (Detail) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016	Dec. 01, 2016
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Embedded Derivative, Fair Value of Embedded Derivative Asset	$ 18,190		$ 10,800
Fair Value, Measurements, Recurring
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative financial instruments - assets	2,043
Embedded Derivative, Fair Value of Embedded Derivative Asset	18,190	$ 10,783
Derivative financial instruments - liabilities	2,602
Fair Value, Measurements, Recurring \| Fair Value, Inputs, Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative financial instruments - assets	0	0
Embedded Derivative, Fair Value of Embedded Derivative Asset	0	0
Derivative financial instruments - liabilities	0	0
Fair Value, Measurements, Recurring \| Significant Other Observable Inputs (Level 2)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative financial instruments - assets	2,043	2,364
Embedded Derivative, Fair Value of Embedded Derivative Asset	18,190	10,783
Derivative financial instruments - liabilities	2,602	7,562
Fair Value, Measurements, Recurring \| Fair Value, Inputs, Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative financial instruments - assets	0	0
Embedded Derivative, Fair Value of Embedded Derivative Asset	0	0
Derivative financial instruments - liabilities	$ 0	$ 0

Fair value as of the balance sheet date of the embedded derivative or group of embedded derivatives classified as an asset.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4B
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=84234895&loc=SL5624163-113959

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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.

+ References

No definition available.

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- Definition

Fair value as of the balance sheet date of interest rate derivative assets, which includes all such derivative instruments in hedging and nonhedging relationships that are recognized as assets.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 10
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=77997519&loc=d3e13433-108611

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- Definition

Fair value as of the balance sheet date of interest rate derivative liabilities, which includes all such derivative instruments in hedging and nonhedging relationships that are recognized as liabilities.

+ References

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