Annual report pursuant to Section 13 and 15(d)

Debt (Narrative) (Details)

v3.6.0.2
Debt (Narrative) (Details)
$ in Millions
 12 Months Ended
Jan. 01, 2017
Jun. 29, 2016
USD ($)
Dec. 31, 2016
USD ($)
Mar. 13, 2017
USD ($)
Jun. 30, 2016
USD ($)
Jun. 28, 2016
Dec. 31, 2015
USD ($)
Jan. 31, 2014
USD ($)
Line Of Credit Facility [Line Items]                
Credit facility borrowing base   $ 20.0     $ 20.0   $ 20.1  
Debt instrument, commitment fee     2.30%          
Line Of Credit Facility Maximum Borrowing Capacity               $ 65.0
Ratio of net debt to EBITDAX     5.0          
Debt service coverage ratio minimum at each quarter     1.2          
Senior Tranche [Member]                
Line Of Credit Facility [Line Items]                
Debt instrument, commitment fee           1.50%    
Line Of Credit Facility Maximum Borrowing Capacity   50.0            
Subordinated Tranche [Member]                
Line Of Credit Facility [Line Items]                
Debt instrument, commitment fee           2.30%    
Line Of Credit Facility Maximum Borrowing Capacity   15.0            
Additional Term Loan [Member]                
Line Of Credit Facility [Line Items]                
Credit facility borrowing base   $ 5.0            
Additional Term Loan [Member] | Subsequent Event [Member]                
Line Of Credit Facility [Line Items]                
Loans Payable       $ 0.0        
Term Loan [Member]                
Line Of Credit Facility [Line Items]                
Debt instrument interest rate spread   5.75%            
Loans Payable   $ 15.0 $ 15.0          
Term loan fair value     $ 15.0          
Loan Agreements, January 1, 2017 to Maturity [Member] | Maximum [Member] | Subsequent Event [Member]                
Line Of Credit Facility [Line Items]                
Ratio of net debt to EBITDAX 3.0