Quarterly report pursuant to Section 13 or 15(d)

RELATED PARTY TRANSACTIONS (Details)

v3.19.2
RELATED PARTY TRANSACTIONS (Details) - USD ($)
$ in Millions
1 Months Ended 3 Months Ended 6 Months Ended 12 Months Ended
Jan. 31, 2018
Jan. 31, 2019
Jun. 30, 2019
Jun. 30, 2018
Jun. 30, 2019
Jun. 30, 2018
Dec. 31, 2018
Related Party Transaction [Line Items]              
Stock repurchased (in shares)     0 0 5,635,000 0 7,360,000
Stock repurchased, value     $ 16.3   $ 16.3    
W Energy Partners LLC | Common Stock              
Related Party Transaction [Line Items]              
Stock repurchased (in shares)   3,700,000          
Stock repurchased, value   $ 11.1          
Subscription Arrangement              
Related Party Transaction [Line Items]              
Sale of stock, percentage of ownership before transaction (in excess) (percent) 5.00%