Subsequent Events - Common Stock Dividend (Details) - $ / shares			3 Months Ended
	Nov. 05, 2018	May 03, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017
Subsequent Event [Line Items]
Quarterly dividend of common stock declared (in dollars per share)		$ 0.1375	$ 0.1375	$ 0.1375	$ 0.1375	$ 0.1375	$ 0.1375	$ 0.1375
Annualized dividend rate (in dollars per share)			$ 0.55
Subsequent Event [Member]
Subsequent Event [Line Items]
Quarterly dividend of common stock declared (in dollars per share)	$ 0.1375
Annualized dividend rate (in dollars per share)	$ 0.55