Quarterly report pursuant to Section 13 or 15(d)

Summary of Long-Term Debt (Detail)

v3.7.0.1
Summary of Long-Term Debt (Detail) - USD ($)
Jun. 30, 2017
Mar. 31, 2017
Dec. 31, 2016
Debt Instrument [Line Items]      
Line of Credit Facility, Maximum Borrowing Capacity   $ 128,000,000  
Revolving credit facility $ 37,000,000   $ 25,000,000
Revolving Credit Facility      
Debt Instrument [Line Items]      
Line of Credit Facility, Maximum Borrowing Capacity $ 200,000,000