Subsequent Events (Details) - USD ($) $ / shares in Units, $ in Thousands			3 Months Ended	6 Months Ended	12 Months Ended
	Oct. 15, 2018	Jul. 19, 2018	Jun. 30, 2018	Jun. 30, 2018	Dec. 31, 2018
Subsequent Event [Line Items]
Dividends paid				$ 4,055
Series A Preferred Stock
Subsequent Event [Line Items]
Dividends paid			$ 2,000	$ 2,900
Series A Preferred Stock | Scenario, Forecast
Subsequent Event [Line Items]
Series A preferred stock dividends declared, annualized (in dollars per share)	$ 2.1875
Dividends paid					$ 8,100
Subsequent Event | Common Class A
Subsequent Event [Line Items]
Class A common stock dividends declared (in dollars per share)		$ 0.18125
Subsequent Event | Series A Preferred Stock
Subsequent Event [Line Items]
Series A preferred stock dividend declared (in dollars per share)		$ 0.546875