Nature of Operations (Details)	Dec. 31, 2016
Related Party Transaction [Line Items]
Percentage of outstanding common stock owned by a partnership in which Mr. Williams' adult children are limited partners	17.30%
Ares Management LLC
Related Party Transaction [Line Items]
Percentage of outstanding common stock beneficially owned	42.00%
Mr. Williams
Related Party Transaction [Line Items]
Percentage of outstanding common stock beneficially owned	17.60%