XML 86 R69.htm IDEA: XBRL DOCUMENT v3.7.0.1
Accounts Payable and Accrued Liabilities - Narrative (Details) - USD ($)
$ in Millions
Jun. 30, 2017
Jun. 30, 2016
Accounts Payable and Accrued Liabilities [Abstract]    
Present value of asset retirement obligation $ 13.4 $ 8.6
Undiscounted value of asset retirement obligation $ 15.0 $ 9.2