Consolidated Balance Sheets (Parenthetical) - USD ($)	Dec. 31, 2017	Dec. 31, 2016
Long-term Debt, Fair Value	$ 398,000,000	$ 0
Preferred Stock
Preferred stock, par value	$ 0.01	$ 0.01
Preferred stock, shares authorized	50,000,000	50,000,000
Preferred stock, shares issued	0	0
Common Series A
Common Stock
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	160,000,000	160,000,000
Common stock, shares issued	54,438,883	54,114,882
Common stock, shares outstanding	54,438,883	54,114,882
Common Series B
Common Stock
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	6,000,000	6,000,000
Common stock, shares issued	2,830,174	2,847,971
Common stock, shares outstanding	2,830,174	2,847,971