Schedule of Fair Value of Notes (Detail) - USD ($) $ in Thousands	Oct. 07, 2017	Dec. 31, 2016
2026 Notes
Fair Value Disclosures [Line Items]
Carrying Value	$ 394,847	$ 394,406
2026 Notes \| Level 2 Inputs
Fair Value Disclosures [Line Items]
Fair Value	395,472
2022 Notes
Fair Value Disclosures [Line Items]
Carrying Value	397,828	$ 397,458
2022 Notes \| Level 2 Inputs
Fair Value Disclosures [Line Items]
Fair Value	$ 426,188

Carrying value as of the balance sheet date of Notes with the highest claim on the assets of the issuer in case of bankruptcy or liquidation (with maturities initially due after one year or beyond the operating cycle if longer), excluding current portion. Senior note holders are paid off in full before any payments are made to junior note holders.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Name:	us-gaap_SeniorLongTermNotes
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant