Quarterly report pursuant to Section 13 or 15(d)

Debt (Details)

v3.7.0.1
Debt (Details) - USD ($)
$ in Thousands
6 Months Ended 79 Months Ended
Jun. 30, 2017
May 12, 2024
May 12, 2017
Dec. 31, 2016
Debt Instrument [Line Items]        
Debt Instrument, Term 7 years      
Debt Instrument, Call Feature 1.0% soft call premium      
Debt Issuance Costs, Gross     $ 6,000  
Unsecured Long-term Debt, Noncurrent $ 415,032     $ 0
Long-term Debt, Maturities, Repayments of Principal, Remainder of Fiscal Year 1,062      
Long-term Debt, Maturities, Repayments of Principal in Year Two 5,313      
Long-term Debt, Maturities, Repayments of Principal in Year Three 4,250      
Long-term Debt, Maturities, Repayments of Principal in Year Four 4,250      
Long-term Debt, Maturities, Repayments of Principal in Year Five 4,250      
Debt Instrument, Annual Principal Payment 405,875      
Long-term Debt, Gross $ 425,000      
Long-term Debt, Description 160.0      
Debt Instrument, Interest Rate, Effective Percentage 4.00%      
Long-term Debt, Fair Value $ 405,000   398,500  
Debt Instrument, Interest Rate, Basis for Effective Rate 0.046      
Debt Instrument, Unamortized Discount     $ 2,100  
Base Rate [Member]        
Debt Instrument [Line Items]        
Debt Instrument, Interest Rate Terms a base rate      
Base Rate [Member] | Applicable Margin - 1.5% [Member]        
Debt Instrument [Line Items]        
Debt Instrument, Interest Rate Terms 0.015      
Federal Funds Effective Swap Rate [Member]        
Debt Instrument [Line Items]        
Debt Instrument, Interest Rate Terms the federal funds rate, plus 0.50%      
Prime Rate [Member]        
Debt Instrument [Line Items]        
Debt Instrument, Interest Rate Terms prime rate      
London Interbank Offered Rate (LIBOR) [Member] | Applicable Margin - 2.5% [Member]        
Debt Instrument [Line Items]        
Debt Instrument, Interest Rate Terms 0.025      
London Interbank Offered Rate (LIBOR) [Member] | Minimum [Member]        
Debt Instrument [Line Items]        
Debt Instrument, Interest Rate Terms adjusted LIBOR rate, subject to a floor of 0.75%      
London Interbank Offered Rate (LIBOR) [Member] | Maximum [Member]        
Debt Instrument [Line Items]        
Debt Instrument, Interest Rate Terms an adjusted LIBOR rate determined on the basis of a one-month interest period, plus 1.0%      
Medium-term Notes [Member]        
Debt Instrument [Line Items]        
Long-term Debt, Gross $ 425,000      
Debt Issuance Costs, Net (5,897)      
Long-term Debt 417,021      
Long-term Debt, Current Maturities (1,989)      
Unsecured Long-term Debt, Noncurrent 415,032      
Debt Instrument, Unamortized Discount $ (2,082)      
Scenario, Forecast [Member]        
Debt Instrument [Line Items]        
Debt Instrument, Frequency of Periodic Payment   quarterly installments    
Debt Instrument, Payment Terms   0.0025