Subsequent Events (Details) - $ / shares		3 Months Ended		6 Months Ended
	Aug. 08, 2019	Mar. 31, 2019	Mar. 31, 2018	Jun. 30, 2019	Jun. 30, 2018
Subsequent Events
Quarterly cash dividends on common stock		$ 0.13	$ 0.10	$ 0.13	$ 0.10
Subsequent Event | Series A Preferred Stock
Subsequent Events
Dividend declared per share of Series A preferred stock	$ 0.384375
Subsequent Event | Dividend Declared | Class A Common Stock
Subsequent Events
Quarterly cash dividends on common stock	$ 0.13