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 ($)
Mar. 31, 2017
Dec. 31, 2016
Debt Instrument [Line Items]    
Line of Credit Facility, Maximum Borrowing Capacity $ 128,000,000 $ 128,000,000
Revolving credit facility 30,000,000 $ 25,000,000
Revolving Credit Facility    
Debt Instrument [Line Items]    
Line of Credit Facility, Maximum Borrowing Capacity $ 200,000,000