Quarterly report pursuant to Section 13 or 15(d)

Long-term Debt - Summary of Company's Current Debt Portfolio (Detail)

v3.8.0.1
Long-term Debt - Summary of Company's Current Debt Portfolio (Detail) - USD ($)
$ in Thousands
Mar. 31, 2018
Dec. 31, 2017
Debt Instrument [Line Items]    
Total principal $ 585,000 $ 585,000
Less: unamortized debt issuance costs (6,596) (7,029)
Total long-term debt 578,404 577,971
6.75% Senior Notes, due July 2022    
Debt Instrument [Line Items]    
Total principal 360,000 360,000
Less: unamortized debt issuance costs (4,400)  
7.50% Senior Notes, due August 2020    
Debt Instrument [Line Items]    
Total principal 225,000 $ 225,000
Less: unamortized debt issuance costs $ (2,200)