Stockholders' Equity - Common Stock Dividends (Details) - $ / shares													3 Months Ended		9 Months Ended
	Oct. 31, 2019	Sep. 10, 2019	Jul. 31, 2019	Jun. 11, 2019	Apr. 30, 2019	Mar. 12, 2019	Jan. 31, 2019	Dec. 12, 2018	Oct. 31, 2018	Sep. 11, 2018	Jul. 31, 2018	Jun. 12, 2018	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Dividends
Dividend per Share, declared		$ 0.40		$ 0.40		$ 0.40		$ 0.40		$ 0.40		$ 0.40	$ 0.40	$ 0.40	$ 1.20	$ 1.17
Dividend per Share, paid	$ 0.40		$ 0.40		$ 0.40		$ 0.40		$ 0.40		$ 0.40