Annual report pursuant to Section 13 and 15(d)

Subsequent Events - Additional Information (Details)

v3.3.1.900
Subsequent Events - Additional Information (Details) - USD ($)
$ in Thousands
2 Months Ended 12 Months Ended
Mar. 31, 2016
Dec. 31, 2015
Feb. 26, 2016
Dec. 31, 2014
Subsequent Event [Line Items]        
Revolving bank credit facility       $ 447,000
Bonds to be secured, date   Mar. 29, 2016    
Subsequent Event        
Subsequent Event [Line Items]        
Revolving bank credit facility     $ 340,000  
Cash balance after borrowing     447,000  
Line of credit, borrowing availability     $ 9,100  
Obligation to secure financial assurances $ 260,800